2009—Net cash provided by operating activities in 2009 decreased $427 million as compared with 2008, due primarily to an increase in trade working capital of $366 million and an increase in deferred income taxes of $108 million.
The trade working capital change resulted primarily from the unfavorable impact of delayed customer billings associated with negative performance adjustments on the LPD-22 through LPD- 25 contract due to projected cost increases at completion.
See Note 7: Contract Charges in Item 8.
The change in deferred taxes was due to the timing of contract related deductions.
U. S.  federal income tax payments made by Northrop Grumman on our behalf were $132 million in 2009.
Investing Activities 2011—Cash used by investing activities was $197 million in 2011, consisting entirely of capital expenditures.2010—Cash used by investing activities was $189 million in 2010, principally for capital expenditures.2009—Cash used by investing activities was $178 million in 2009, due principally to $181 million in capital expenditures.
Financing Activities 2011—Cash provided by financing activities in 2011 was $584 million.
Our cash flow from financing activities resulted primarily from the issuance of $1,775 million of debt, of which $22 million was repaid in 2011, and a $1,266 million net transfer from our former parent, offset by $54 million of debt issuance costs, repayment of $954 million of notes to our former parent, and a contribution of $1,429 million to Northrop Grumman as a result of the spin-off.2010—In anticipation of the spin-off, on November 30, 2010, NGSB purchased $178 million of the outstanding principal amount of GO Zone IRBs pursuant to a tender offer.
NGSB used the proceeds of an intercompany loan for $178 million with Northrop Grumman to purchase the GO Zone IRBs and submitted the purchased bonds to the trustee for cancellation.
See Note 13: Debt in Item 8.
For the year ended December 31, 2010 and prior, transactions between Northrop Grumman and us were reflected as effectively settled for cash at the time of the transaction and are included in financing activities in our consolidated statements of cash flows.
The net effect of these transactions is reflected in Former Parent’s Equity in Unit in our consolidated statements of financial position.
Free Cash Flow Free cash flow represents cash provided by (used in) operating activities less capital expenditures.
We believe free cash flow is a useful measure for investors to consider.
Free cash flow is not a measure of financial performance under GAAP, and may not be defined and calculated by other companies in the same manner.
This measure should not be considered in isolation, as a measure of residual cash flow available for discretionary purposes, or as an alternative to operating results presented in accordance with GAAP as indicators of performance.
The table below reconciles net cash provided by (used in) operating activities to free cash flow:
## Table 0 ##
Pension Plan Contributions We make both required and discretionary contributions to our defined benefit pension plans.
Our policy is to fund our qualified defined benefit pension plans at least to the minimum amounts required under U. S.  Government regulations.
17.
EMPLOYEE PENSION AND OTHER POSTRETIREMENT BENEFITS The Company provides eligible employees defined benefit pension plans and postretirement benefit plans.
Noncollectively bargained defined benefit pension benefits accruing under the traditional years of service and compensation formula were amended in 2009 to freeze future service accruals and have been replaced with a cash balance benefit for all current non-collectively bargained employees.
Except for the major collectively bargained plan at Ingalls, the Company's qualified defined benefit pension plans are frozen to new entrants.
The Company's policy is to fund its qualified defined benefit pension plans at least to the minimum amounts required under U. S.  Government regulations.
Plan obligations are measured based on the present value of projected future benefit payments to participants for services rendered to date.
The measurement of projected future benefits is dependent on the terms of each individual plan, demographics, and valuation assumptions.
No assumption is made regarding any potential changes to the benefit provisions beyond those to which the Company is currently committed, for example under existing collective bargaining agreements.
The Company also sponsors 401(k) defined contribution pension plans in which most employees, including certain hourly employees, are eligible to participate.
Company contributions for most defined contribution pension plans are based on the matching of employee contributions up to 4% of eligible compensation.
Certain hourly employees are covered under a target benefit plan.
In addition to the 401(k) defined contribution pension benefit formula, noncollectively bargained employees hired after June 30, 2008, are eligible to participate in a defined contribution benefit program in lieu of a defined benefit pension plan.
The Company's contributions to the qualified defined contribution pension plans for the years ended December 31, 2018, 2017, and 2016, were $102 million, $78 million, and $71 million, respectively.
The Company also sponsors defined benefit and defined contribution pension plans to provide benefits in excess of the tax-qualified limits.
The liabilities related to these plans as of December 31, 2018, were $183 million and $30 million, respectively, and as of December 31, 2017, were $182 million and $32 million, respectively.
Assets, primarily in the form of Level 1 marketable securities held in grantor trusts, are intended to fund certain of these obligations.
The trusts’ fair values supporting these liabilities as of December 31, 2018 and 2017, were $109 million and $94 million, respectively, of which $78 million and $61 million, respectively, were related to the non-qualified defined benefit pension plans.
The Company provides contributory postretirement health care and life insurance benefits to a dominantly closed group of eligible employees, retirees, and their qualifying dependents.
Covered employees achieve eligibility to participate in these contributory plans upon retirement from active service if they meet specified age, years of service, and grandfathered requirements.
Benefits are not guaranteed, and the Company reserves the right to amend or terminate coverage at any time.
The Company's contributions for retiree health care benefits are subject to caps, which limit Company contributions when spending thresholds are reached.
The measurement date for all of the Company's retirement related plans is December 31.
The costs of the Company's defined benefit pension plans and other postretirement benefit plans for the years ended December 31, 2018, 2017, and 2016, were as follows:
## Table 1 ##
Pension Plan Assets Pension assets include public equities, government and corporate bonds, cash and cash equivalents, private real estate funds, private partnerships, hedge funds, and other assets.
Plan assets are held in a master trust and overseen by the Company's Investment Committee.
All assets are externally managed through a combination of active and passive strategies.
Managers may only invest in the asset classes for which they have been appointed.
The Investment Committee is responsible for setting the policy that provides the framework for management of the plan assets.
The Investment Committee has set the minimum and maximum permitted values for each asset class in the Company's pension plan master trust for the year ended December 31, 2018, as follows:
## Table 2 ##
The general objectives of the Company's pension asset strategy are to earn a rate of return over time to satisfy the benefit obligations of the plans, meet minimum ERISA funding requirements, and maintain sufficient liquidity to pay benefits and address other cash requirements within the master trust.
Specific investment objectives include reducing the volatility of pension assets relative to benefit obligations, achieving a competitive, total investment return, achieving diversification between and within asset classes, and managing other risks.
Investment objectives for each asset class are determined based on specific risks and investment opportunities identified.
Decisions regarding investment policies and asset allocation are made with the understanding of the historical and prospective return and risk characteristics of various asset classes, the effect of asset allocations on funded status, future Company contributions, and projected expenditures, including benefits.
The Company updates its asset allocations periodically.
The Company uses various analytics to determine the optimal asset mix and considers plan obligation characteristics, duration, liquidity characteristics, funding requirements, expected rates of return, regular rebalancing, and the distribution of returns.
Actual allocations to each asset class could vary from target allocations due to periodic investment strategy changes, short-term market value fluctuations, the length of time it takes to fully implement investment allocation positions, such as real estate and other alternative investments, and the timing of benefit payments and Company contributions.
Taking into account the asset allocation ranges, the Company determines the specific allocation of the master trust's investments within various asset classes.
The master trust utilizes select investment strategies, which are executed through separate account or fund structures with external investment managers who demonstrate experience and expertise in the appropriate asset classes and styles.
The selection of investment managers is done with careful evaluation of all aspects of performance and risk, demonstrated fiduciary responsibility, investment management experience, and a review of the investment managers' policies and processes.
Investment performance is monitored frequently against appropriate benchmarks and tracked to compliance guidelines with the assistance of third party consultants and performance evaluation tools and metrics.
Plan assets are stated at fair value.
The Company employs a variety of pricing sources to estimate the fair value of its pension plan assets, including independent pricing vendors, dealer or counterparty-supplied valuations, thirdparty appraisals, and appraisals prepared by the Company's investment managers or other experts.
Investments in equity securities, common and preferred, are valued at the last reported sales price when an active market exists.
Securities for which official or last trade pricing on an active exchange is available are classified as Level 1.
If closing prices are not available, securities are valued at the last trade price, if deemed reasonable, or a broker's quote in a non-active market, and are typically categorized as Level 2.
Investments in fixed-income securities are generally valued by independent pricing services or dealers who make markets in such securities.
Pricing methods are based upon market transactions for comparable securities and various relationships between securities that are generally recognized by institutional traders, and fixed-income securities typically are categorized as Level 2.

<table><tr><td></td><td colspan="5">Year Ended December 31</td></tr><tr><td> ($ in millions)</td><td>2011</td><td>2010</td><td>2009</td><td>2008</td><td>2007</td></tr><tr><td>Net cash provided by (used in) operating activities</td><td>$528</td><td>$359</td><td>$-88</td><td>$339</td><td>$610</td></tr><tr><td>Less:</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Capital expenditures</td><td>-197</td><td>-191</td><td>-181</td><td>-218</td><td>-246</td></tr><tr><td>Free cash flow from operations</td><td>$331</td><td>$168</td><td>$-269</td><td>$121</td><td>$364</td></tr></table>
<table><tr><td></td><td colspan="3">Pension Benefits Year Ended December 31</td><td colspan="3">Other Benefits Year Ended December 31</td></tr><tr><td>($ in millions)</td><td>2018</td><td>2017</td><td>2016</td><td>2018</td><td>2017</td><td>2016</td></tr><tr><td>Components of Net Periodic Benefit Cost</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Service cost</td><td>$157</td><td>$146</td><td>$133</td><td>$8</td><td>$10</td><td>$10</td></tr><tr><td>Interest cost</td><td>254</td><td>266</td><td>262</td><td>21</td><td>24</td><td>25</td></tr><tr><td>Expected return on plan assets</td><td>-429</td><td>-367</td><td>-346</td><td>—</td><td>—</td><td>—</td></tr><tr><td>Amortization of prior service cost (credit)</td><td>24</td><td>20</td><td>18</td><td>-22</td><td>-20</td><td>-19</td></tr><tr><td>Amortization of net actuarial loss (gain)</td><td>81</td><td>97</td><td>84</td><td>-3</td><td>-4</td><td>-6</td></tr><tr><td>Net periodic benefit cost</td><td>$87</td><td>$162</td><td>$151</td><td>$4</td><td>$10</td><td>$10</td></tr></table>
<table><tr><td></td><td>Range</td></tr><tr><td>U.S. equities</td><td>15</td><td>-</td><td>36%</td></tr><tr><td>International equities</td><td>10</td><td>-</td><td>29%</td></tr><tr><td>Fixed income securities</td><td>25</td><td>-</td><td>50%</td></tr><tr><td>Alternative investments</td><td>10</td><td>-</td><td>25%</td></tr></table>

Question: What do all elements for Pension Benefits Year Ended December 31 sum up, excluding those negative ones in 2018 ? (in million)
Answer: 516