System Energy Resources, Inc.  Management’s Financial Discussion and Analysis System Energy may refinance, redeem, or otherwise retire debt prior to maturity, to the extent market conditions and interest and dividend rates are favorable.
All debt and common stock issuances by System Energy require prior regulatory approval. ?
?Debt issuances are also subject to issuance tests set forth in its bond indentures and other agreements. ?
?System Energy has sufficient capacity under these tests to meet its foreseeable capital needs.
System Energy’s receivables from the money pool were as follows as of December 31 for each of the following years.
## Table 0 ##
See Note 4 to the financial statements for a description of the money pool.
The System Energy nuclear fuel company variable interest entity has a credit facility in the amount of $120 million scheduled to expire in May 2019.
As of December 31, 2017, $17.8 million in letters of credit to support a like amount of commercial paper issued and $50 million in loans were outstanding under the System Energy nuclear fuel company variable interest entity credit facility.
See Note 4 to the financial statements for additional discussion of the variable interest entity credit facility.
System Energy obtained authorizations from the FERC through October 2019 for the following: ?
short-term borrowings not to exceed an aggregate amount of $200 million at any time outstanding; ?
long-term borrowings and security issuances; and ?
long-term borrowings by its nuclear fuel company variable interest entity.
See Note 4 to the financial statements for further discussion of System Energy’s short-term borrowing limits.
System Energy Resources, Inc.  Management’s Financial Discussion and Analysis 425 Federal Regulation See the “Rate, Cost-recovery, and Other Regulation – Federal Regulation” section of Entergy Corporation and Subsidiaries Management’s Financial Discussion and Analysis and Note 2 to the financial statements for a discussion of federal regulation.
Complaint Against System Energy In January 2017 the APSC and MPSC filed a complaint with the FERC against System Energy.
The complaint seeks a reduction in the return on equity component of the Unit Power Sales Agreement pursuant to which System Energy sells its Grand Gulf capacity and energy to Entergy Arkansas, Entergy Louisiana, Entergy Mississippi, and Entergy New Orleans.
Entergy Arkansas also sells some of its Grand Gulf capacity and energy to Entergy Louisiana, Entergy Mississippi, and Entergy New Orleans under separate agreements.
The current return on equity under the Unit Power Sales Agreement is 10.94%.
The complaint alleges that the return on equity is unjust and unreasonable because current capital market and other considerations indicate that it is excessive.
The complaint requests the FERC to institute proceedings to investigate the return on equity and establish a lower return on equity, and also requests that the FERC establish January 23, 2017 as a refund effective date.
The complaint includes return on equity analysis that purports to establish that the range of reasonable return on equity for System Energy is between 8.37% and 8.67%.
System Energy answered the complaint in February 2017 and disputes that a return on equity of 8.37% to 8.67% is just and reasonable.
The LPSC and the City Council intervened in the proceeding expressing support for the complaint.
System Energy is recording a provision against revenue for the potential outcome of this proceeding.
In September 2017 the FERC established a refund effective date of January 23, 2017, consolidated the return on equity complaint with the proceeding described in Unit Power Sales Agreement below, and directed the parties to engage in settlement
A reconciliation of our AROs is as follows:
## Table 1 ##
North America Gypstack Closure Costs A majority of our ARO relates to Gypstack Closure Costs in Florida and Louisiana.
For financial reporting purposes, we recognize our estimated Gypstack Closure Costs at their present value.
This present value determined for financial reporting purposes is reflected on our Consolidated Balance Sheets in accrued liabilities and other noncurrent liabilities.
As of December 31, 2018, and December 31, 2017, the present value of our Gypstack Closure Costs ARO reflected in our Consolidated Balance Sheet was approximately $578.4 million and $529.7 million, respectively.
As discussed below, we have arrangements to provide financial assurance for the estimated Gypstack Closure Costs associated with our facilities in Florida and Louisiana.
EPA RCRA Initiative.
On September 30, 2015, we and our subsidiary, Mosaic Fertilizer, LLC (“Mosaic Fertilizer”), reached agreements with the U. S.  Environmental Protection Agency (“EPA”), the U. S.  Department of Justice (“DOJ”), the Florida Department of Environmental Protection (“FDEP”) and the Louisiana Department of Environmental Quality (“LDEQ”) on the terms of two consent decrees (collectively, the “2015 Consent Decrees”) to resolve claims relating to our management of certain waste materials onsite at our Riverview, New Wales, Mulberry, Green Bay, South Pierce and Bartow fertilizer manufacturing facilities in Florida and our Faustina and Uncle Sam facilities in Louisiana.
This followed a 2003 announcement by the EPA Office of Enforcement and Compliance Assurance that it would be targeting facilities in mineral processing industries, including phosphoric acid producers, for a thorough review under the U. S.  Resource Conservation and Recovery Act (“RCRA”) and related state laws.
As discussed below, a separate consent decree was previously entered into with EPA and the FDEP with respect to RCRA compliance at the Plant City, Florida phosphate concentrates facility (the “Plant City Facility”) that we acquired as part of our acquisition (the “CF Phosphate Assets Acquisition”) of the Florida phosphate assets and assumption of certain related liabilities of CF Industries, Inc.  (“CF”).
The remaining monetary obligations under the 2015 Consent Decrees include: ?
Modification of certain operating practices and undertaking certain capital improvement projects over a period of several years that are expected to result in capital expenditures likely to exceed $200 million in the aggregate.  ?
Provision of additional financial assurance for the estimated Gypstack Closure Costs for Gypstacks at the covered facilities.
The RCRA Trusts are discussed in Note 12 to our Consolidated Financial Statements.
In addition, we have agreed to guarantee the difference between the amounts held in each RCRA Trust (including any earnings) and the estimated closure and long-term care costs.
As of December 31, 2018, the undiscounted amount of our Gypstack Closure Costs ARO associated with the facilities covered by the 2015 Consent Decrees, determined using the assumptions used for financial reporting purposes, was approximately $1.5 billion, and the present value of our Gypstack Closure Costs ARO reflected in our Consolidated Balance Sheet for those facilities was approximately $457.1 million.
In December 2016, we entered into forward starting interest rate swap agreements to hedge our exposure to changes in future interest rates related to an anticipated debt issuance to fund the cash portion of the Acquisition as described in Note 24.
We did not apply hedge accounting treatment to these contracts, and we used cash to settle our obligation at the time of pricing of the related debt.
In November 2017, we completed the debt issuance and settled all of our outstanding pre-issuance interest rate swap agreements.
These agreements had a negative impact on pre-tax earnings of approximately $12 million for the year ended December 31, 2017.
The following is the total absolute notional volume associated with our outstanding derivative instruments: (in millions of Units)
## Table 2 ##
Credit-Risk-Related Contingent Features Certain of our derivative instruments contain provisions that are governed by International Swap and Derivatives Association agreements with the counterparties.
These agreements contain provisions that allow us to settle for the net amount between payments and receipts, and also state that if our debt were to be rated below investment grade, certain counterparties to the derivative instruments could request full collateralization on derivative instruments in net liability positions.
The aggregate fair value of all derivative instruments with credit-risk-related contingent features that were in a liability position as of December 31, 2018, and 2017 was $37.9 million and $15.0 million, respectively.
We have no cash collateral posted in association with these contracts.
If the credit-risk-related contingent features underlying these agreements were triggered on December 31, 2018, we would have been required to post an additional $36.8 million of collateral assets, which are either cash or U. S.  Treasury instruments, to the counterparties.
Counterparty Credit Risk We enter into foreign exchange, certain commodity and interest rate derivatives, primarily with a diversified group of highly rated counterparties.
We continually monitor our positions and the credit ratings of the counterparties involved and limit the amount of credit exposure to any one party.
While we may be exposed to potential losses due to the credit risk of nonperformance by these counterparties, material losses are not anticipated.
We closely monitor the credit risk associated with our counterparties and customers and to date have not experienced material losses.16.
FAIR VALUE MEASUREMENTS Following is a summary of the valuation techniques for assets and liabilities recorded in our Consolidated Balance Sheets at fair value on a recurring basis: Foreign Currency Derivatives—The foreign currency derivative instruments that we currently use are forward contracts and zero-cost collars, which typically expire within eighteen months.
Most of the valuations are adjusted by a forward yield curve or interest rates.
In such cases, these derivative contracts are classified within Level 2.
Some valuations are based on exchange-quoted prices, which are classified as Level 1.
Changes in the fair market values of these contracts are recognized in the Consolidated Financial Statements as a component of cost of goods sold in our Corporate, Eliminations and Other segment, or foreign currency transaction (gain) loss.
As of December 31, 2018 and 2017, the gross asset position of our foreign currency derivative instruments was $13.1 million and $15.4 million, respectively, and the gross liability position of our foreign currency derivative instruments was $62.2 million and $6.5 million, respectively.
Commodity Derivatives—The commodity contracts primarily relate to natural gas.
The commodity derivative instruments that we currently use are forward purchase contracts, swaps, and three-way collars.
The natural gas contracts settle using NYMEX futures or AECO price indexes, which represent fair value at any given time.
The contracts’ maturities and settlements are scheduled for future months and settlements are scheduled to coincide with anticipated gas purchases during those future periods.
Quoted market prices from NYMEX and AECO are used to determine the fair value of these instruments.
These market prices are adjusted by a forward yield curve and are classified within Level 2.
Changes in the fair
Segment information for the years 2018, 2017 and 2016 is as follows:
## Table 3 ##
(a) The "Corporate, Eliminations and Other" category includes the results of our ancillary distribution operations in India and China.
For the years ended December 31, 2018, 2017 and 2016, distribution operations in India and China had revenues of $533.9 million, $493.2 million, and $419.6 million, respectively and gross margins of $42.8 million, $46.9 million, and $21.2 million, respectively.

Tables referenced above, in order (Table 0 first):
<table><tr><td>2017</td><td>2016</td><td>2015</td><td>2014</td></tr><tr><td>(In Thousands)</td></tr><tr><td>$111,667</td><td>$33,809</td><td>$39,926</td><td>$2,373</td></tr></table>
<table><tr><td></td><td colspan="2">Years Ended December 31,</td></tr><tr><td>(in millions)</td><td>2018</td><td>2017</td></tr><tr><td>AROs, beginning of period</td><td>$859.3</td><td>$849.9</td></tr><tr><td>Liabilities acquired in the Acquisition</td><td>258.9</td><td>—</td></tr><tr><td>Liabilities incurred</td><td>27.8</td><td>27.1</td></tr><tr><td>Liabilities settled</td><td>-69.6</td><td>-64.8</td></tr><tr><td>Accretion expense</td><td>48.0</td><td>25.7</td></tr><tr><td>Revisions in estimated cash flows</td><td>78.2</td><td>15.7</td></tr><tr><td>Foreign currency translation</td><td>-42.5</td><td>5.7</td></tr><tr><td>AROs, end of period</td><td>1,160.1</td><td>859.3</td></tr><tr><td>Less current portion</td><td>136.3</td><td>98.1</td></tr><tr><td></td><td>$1,023.8</td><td>$761.2</td></tr></table>
<table><tr><td>Instrument</td><td>Derivative Category</td><td>Unit of Measure</td><td>December 31,2018</td><td>December 31,2017</td></tr><tr><td>Foreign currency derivatives</td><td>Foreign Currency</td><td>US Dollars</td><td>2,091.7</td><td>813.5</td></tr><tr><td>Interest rate derivatives</td><td>Interest Rate</td><td>US Dollars</td><td>585.0</td><td>585.0</td></tr><tr><td>Natural gas derivatives</td><td>Commodity</td><td>MMbtu</td><td>52.2</td><td>43.0</td></tr></table>
<table><tr><td>(in millions)</td><td>Phosphates</td><td>Potash</td><td>Mosaic Fertilizantes</td><td>Corporate,Eliminationsand Other (a)</td><td>Total</td></tr><tr><td>Year Ended December 31, 2018</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Net sales to external customers</td><td>$3,106.3</td><td>$2,154.8</td><td>$3,747.1</td><td>$579.1</td><td>$9,587.3</td></tr><tr><td>Intersegment net sales</td><td>780.0</td><td>19.1</td><td>—</td><td>-799.1</td><td>—</td></tr><tr><td>Net sales</td><td>3,886.3</td><td>2,173.9</td><td>3,747.1</td><td>-220.0</td><td>9,587.3</td></tr><tr><td>Gross margin</td><td>581.5</td><td>597.2</td><td>382.9</td><td>-63.2</td><td>1,498.4</td></tr><tr><td>Canadian resource taxes</td><td>—</td><td>159.4</td><td>—</td><td>—</td><td>159.4</td></tr><tr><td>Gross margin (excluding Canadian resource taxes)</td><td>581.5</td><td>756.6</td><td>382.9</td><td>-63.2</td><td>1,657.8</td></tr><tr><td>Operating earnings</td><td>414.8</td><td>454.1</td><td>227.0</td><td>-167.6</td><td>928.3</td></tr><tr><td>Capital expenditures</td><td>393.9</td><td>410.5</td><td>148.2</td><td>1.9</td><td>954.5</td></tr><tr><td>Depreciation, depletion and amortization expense</td><td>403.7</td><td>301.5</td><td>158.5</td><td>20.2</td><td>883.9</td></tr><tr><td>Equity in net earnings (loss) of nonconsolidated companies</td><td>-4.6</td><td>—</td><td>—</td><td>0.1</td><td>-4.5</td></tr><tr><td>Year Ended December 31, 2017</td><td></td><td></td><td></td><td></td><td>—</td></tr><tr><td>Net sales to external customers</td><td>$2,826.6</td><td>$1,836.5</td><td>$2,220.1</td><td>$526.2</td><td>$7,409.4</td></tr><tr><td>Intersegment net sales</td><td>762.6</td><td>16.1</td><td>—</td><td>-778.7</td><td>—</td></tr><tr><td>Net sales</td><td>3,589.2</td><td>1,852.6</td><td>2,220.1</td><td>-252.5</td><td>7,409.4</td></tr><tr><td>Gross margin</td><td>332.2</td><td>391.6</td><td>128.6</td><td>-9.6</td><td>842.8</td></tr><tr><td>Canadian resource taxes</td><td>—</td><td>70.1</td><td>—</td><td>—</td><td>70.1</td></tr><tr><td>Gross margin (excluding Canadian resource taxes)</td><td>332.2</td><td>461.7</td><td>128.6</td><td>-9.6</td><td>912.9</td></tr><tr><td>Operating earnings</td><td>191.6</td><td>281.3</td><td>63.1</td><td>-70.3</td><td>465.7</td></tr><tr><td>Capital expenditures</td><td>401.0</td><td>371.6</td><td>32.7</td><td>14.8</td><td>820.1</td></tr><tr><td>Depreciation, depletion and amortization expense</td><td>338.0</td><td>287.2</td><td>16.9</td><td>23.4</td><td>665.5</td></tr><tr><td>Equity in net earnings (loss) of nonconsolidated companies</td><td>16.0</td><td>—</td><td>—</td><td>0.7</td><td>16.7</td></tr><tr><td>Year Ended December 31, 2016</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Net sales to external customers</td><td>$2,928.4</td><td>$1,673.0</td><td>$2,113.9</td><td>$447.5</td><td>$7,162.8</td></tr><tr><td>Intersegment net sales</td><td>782.5</td><td>12.7</td><td>—</td><td>-795.2</td><td>—</td></tr><tr><td>Net sales</td><td>3,710.9</td><td>1,685.7</td><td>2,113.9</td><td>-347.7</td><td>7,162.8</td></tr><tr><td>Gross margin</td><td>349.8</td><td>256.6</td><td>125.0</td><td>78.6</td><td>810.0</td></tr><tr><td>Canadian resource taxes</td><td>—</td><td>101.1</td><td>—</td><td>—</td><td>101.1</td></tr><tr><td>Gross margin (excluding Canadian resource taxes)</td><td>349.8</td><td>357.7</td><td>125.0</td><td>78.6</td><td>911.1</td></tr><tr><td>Operating earnings</td><td>47.8</td><td>138.8</td><td>64.8</td><td>67.6</td><td>319.0</td></tr><tr><td>Capital expenditures</td><td>380.0</td><td>416.7</td><td>23.7</td><td>22.7</td><td>843.1</td></tr><tr><td>Depreciation, depletion and amortization expense</td><td>362.4</td><td>308.7</td><td>15.1</td><td>25.0</td><td>711.2</td></tr><tr><td>Equity in net earnings (loss) of nonconsolidated companies</td><td>0.2</td><td>-15.5</td><td>-0.1</td><td>—</td><td>-15.4</td></tr><tr><td>Total assets as of December 31, 2018</td><td>$7,877.3</td><td>$7,763.1</td><td>$3,952.4</td><td>$526.4</td><td>$20,119.2</td></tr><tr><td>Total assets as of December 31, 2017</td><td>7,700.6</td><td>8,301.7</td><td>1,376.7</td><td>1,254.4</td><td>18,633.4</td></tr><tr><td>Total assets as of December 31, 2016</td><td>7,679.7</td><td>7,777.9</td><td>1,249.7</td><td>133.4</td><td>16,840.7</td></tr></table>

Question: What's the average of AROs, end of period of Years Ended December 31, 2018, and Net sales of Phosphates ?
Answer: 2523.2
Reasoning program: add(1160.1,3886.3), divide(#0,const_2)