d as a financing activity rather than an operating activity in the statements of cash flows.
We adopted SFAS 123R on January 1, 2006 under the retrospective transition method using the Black-Scholes pricing model.
The effect of expensing stock options under a fair value approach using the Black-Scholes pricing model on diluted earnings per common share for the years ended December 31, 2005, 2004 and 2003 is disclosed on page 69.
In addition, the classification of cash inflows from any excess tax benefit associated with exercising stock options will change from an operating activity to a financing activity in the consolidated statements of cash flows with no impact on total cash flows.
We estimate the impact of this change in classification will decrease operating cash flows (and increase financing cash flows) by approximately $15.5 million in 2005, $3.7 million in 2004, and $15.2 million in 2003.
Stock option expense after adopting SFAS 123R is not expected to be materially different than our pro forma disclosure on page 69 and is dependent on levels of stock options granted during 2006.3.
ACQUISITIONS In January 2006, our Commercial segment reached an agreement to acquire CHA Service Company, or CHA Health, a health plan serving employer groups in Kentucky, for cash consideration of approximately $60.0 million plus any excess statutory surplus.
This transaction, which is subject to regulatory approval, is expected to close effective in the second quarter of 2006.
On December 20, 2005, our Commercial segment acquired Corphealth, Inc. , or Corphealth, a behavioral health care management company, for cash consideration of approximately $54.2 million, including transaction costs.
This acquisition allows Humana to integrate coverage of medical and behavior health benefits.
Net tangible assets acquired of $6.0 million primarily consisted of cash and cash equivalents.
The purchase price exceeded the estimated fair value of the net tangible assets acquired by approximately $48.2 million.
We preliminarily allocated this excess purchase price to other intangible assets of $8.6 million and associated deferred tax liabilities of $3.2 million, and non-deductible goodwill of $42.8 million.
The other intangible assets, which consist primarily of customer contracts, have a weighted average useful life of 14.7 years.
The allocation is subject to change pending completion of the valuation by a third party valuation specialist firm assisting us in evaluating the fair value of the assets acquired.
On February 16, 2005, our Government segment acquired CarePlus Health Plans of Florida, or CarePlus, as well as its affiliated 10 medical centers and pharmacy company.
CarePlus provides Medicare Advantage HMO plans and benefits to Medicare Advantage members in Miami-Dade, Broward and Palm Beach counties.
This acquisition enhances our Medicare market position in South Florida.
We paid approximately $444.9 million in cash, including transaction costs.
We financed the transaction with $294.0 million of borrowings under our credit agreement and $150.9 million of cash on hand.
The purchase price is subject to a balance sheet settlement process with a nine month claims run-out period.
This settlement, which will be reflected as an adjustment to goodwill, is not expected to be material.
The fair value of the acquired tangible assets (assumed liabilities) consisted of the following:
## Table 0 ##
Regulatory Requirements Certain of our subsidiaries operate in states that regulate the payment of dividends, loans, or other cash transfers to Humana Inc. , our parent company, and require minimum levels of equity as well as limit investments to approved securities.
The amount of dividends that may be paid to Humana Inc.  by these subsidiaries, without prior approval by state regulatory authorities, or ordinary dividends, is limited based on the entity’s level of statutory income and statutory capital and surplus.
In most states, prior notification is provided before paying a dividend even if approval is not required.
Actual dividends paid may vary due to consideration of excess statutory capital and surplus and expected future surplus requirements related to, for example, premium volume and product mix.
Although minimum required levels of equity are largely based on premium volume, product mix, and the quality of assets held, minimum requirements vary significantly at the state level.
Our state regulated subsidiaries had aggregate statutory capital and surplus of approximately $5.1 billion and $4.7 billion as of December 31, 2012 and 2011, respectively, which exceeded aggregate minimum regulatory requirements.
Excluding Puerto Rico subsidiaries, the amount of ordinary dividends that may be paid to our parent company in 2013 is approximately $911 million in the aggregate.
This compares to ordinary dividends that were able to be paid in 2012 of approximately $860 million.
We expect the amount of dividends to be paid to our parent company in 2013 to approximate the amount of ordinary dividends.
Contractual Obligations We are contractually obligated to make payments for years subsequent to December 31, 2012 as follows:
## Table 1 ##
(1) Interest includes the estimated contractual interest payments under our debt agreements.
(2) We lease facilities, computer hardware, and other furniture and equipment under long-term operating leases that are noncancelable and expire on various dates through 2025.
We sublease facilities or partial facilities to third party tenants for space not used in our operations which partially mitigates our operating lease commitments.
An operating lease is a type of off-balance sheet arrangement.
Assuming we acquired the asset, rather than leased such asset, we would have recognized a liability for the financing of these assets.
See also Note 15 to the consolidated financial statements included in Item 8.
– Financial Statements and Supplementary Data.
(3) Purchase obligations include agreements to purchase services, primarily information technology related services, or to make improvements to real estate, in each case that are enforceable and legally binding on us and that specify all significant terms, including: fixed or minimum levels of service to be purchased; fixed, minimum or variable price provisions; and the appropriate timing of the transaction.
Purchase obligations exclude agreements that are cancelable without penalty.
(4) Includes future policy benefits payable ceded to third parties through 100% coinsurance agreements as more fully described in Note 18 to the consolidated financial statements included in Item 8.
– Financial Statements and Supplementary Data.
We expect the assuming reinsurance carriers to fund these obligations
that limited the underwriting profit to 10% of the target cost.
We paid 20% for any cost overrun, subject to a floor that limited the underwriting loss to negative 4% of the target cost.
A final settlement occurred 12 to 18 months after the end of each contract year to which it applied.
We deferred the recognition of any revenues for favorable contingent underwriting fee adjustments related to cost underruns until the amount was determinable and the collectibility was reasonably assured.
We estimated and recognized unfavorable contingent underwriting fee adjustments related to cost overruns currently in operations as an increase in benefits expense.
The military services contracts contain provisions to negotiate change orders.
Change orders occur when we perform services or incur costs under the directive of the federal government that were not originally specified in our contract.
Under federal regulations we may be entitled to an equitable adjustment to the contract price in these situations.
Change orders may be negotiated and settled at any time throughout the year.
We record revenue applicable to change orders when services are performed and these amounts are determinable and the collectibility is reasonably assured.
Patient Services Patient services revenue associated with provider services in our Health and Well-Being Services segment primarily related to Concentra, acquired December 21, 2010.
Patient services revenue includes (1) workers’ compensation injury care and related services and (2) other healthcare services related to employer needs or statutory requirements.
Patient services revenues are recognized in the period services are provided to the customer when the sales price is fixed or determinable, and are net of contractual allowances.
The provider reimbursement methods for workers’ compensation injury care and related services vary on a state-by-state basis.
Most states have fee schedules pursuant to which all healthcare providers are uniformly reimbursed.
The fee schedules are determined by each state and generally prescribe the maximum amounts that may be reimbursed for a designated procedure.
In the states without fee schedules, healthcare providers are reimbursed based on usual, customary, and reasonable fees charged in the particular state in which the services are provided.
We include billings for services in revenue net of allowance for estimated differences between list prices and allowable fee schedule rates or amounts allowed as usual, customary and reasonable, as applicable.
Revenue for other healthcare services is recognized on a fee-for-service basis at estimated collectible amounts at the time services are rendered.
Our fees are determined in advance for each type of service performed.
Investment Securities Investment securities totaled $9.8 billion, or 49% of total assets at December 31, 2012, and $9.5 billion, or 53% of total assets at December 31, 2011.
Debt securities, detailed below, comprised this entire investment portfolio at December 31, 2012 and at December 31, 2011.
The fair value of debt securities were as follows at December 31, 2012 and 2011:
## Table 2 ##

<table><tr><td></td><td>(in thousands)</td></tr><tr><td>Cash and cash equivalents</td><td>$92,116</td></tr><tr><td>Premiums receivable and other current assets</td><td>6,510</td></tr><tr><td>Property and equipment and other assets</td><td>21,315</td></tr><tr><td>Medical and other expenses payable</td><td>-37,375</td></tr><tr><td>Other current liabilities</td><td>-23,359</td></tr><tr><td>Other liabilities</td><td>-5,915</td></tr><tr><td>Net tangible assets acquired</td><td>$53,292</td></tr></table>
<table><tr><td></td><td colspan="5"> Payments Due by Period</td></tr><tr><td></td><td> Total</td><td> Less than 1 Year</td><td> 1-3 Years</td><td> 3-5 Years</td><td> More than 5 Years</td></tr><tr><td></td><td colspan="5"> (in millions)</td></tr><tr><td>Debt</td><td>$2,550</td><td>$0</td><td>$0</td><td>$500</td><td>$2,050</td></tr><tr><td>Interest -1</td><td>1,694</td><td>146</td><td>293</td><td>243</td><td>1,012</td></tr><tr><td>Operating leases -2</td><td>852</td><td>212</td><td>326</td><td>192</td><td>122</td></tr><tr><td>Purchase obligations -3</td><td>262</td><td>124</td><td>109</td><td>13</td><td>16</td></tr><tr><td>Future policy benefits payable and otherlong-term liabilities -4</td><td>2,209</td><td>65</td><td>269</td><td>238</td><td>1,637</td></tr><tr><td>Total</td><td>$7,567</td><td>$547</td><td>$997</td><td>$1,186</td><td>$4,837</td></tr></table>
<table><tr><td></td><td> December 31, 2012</td><td>Percentage of Total</td><td> December 31, 2011</td><td> Percentage of Total</td></tr><tr><td></td><td colspan="4"> (dollars in millions)</td></tr><tr><td>U.S. Treasury and other U.S. government corporations and agencies:</td><td></td><td></td><td></td><td></td></tr><tr><td>U.S. Treasury and agency obligations</td><td>$618</td><td>6.3%</td><td>$725</td><td>7.7%</td></tr><tr><td>Mortgage-backed securities</td><td>1,603</td><td>16.3%</td><td>1,784</td><td>18.9%</td></tr><tr><td>Tax-exempt municipal securities</td><td>3,071</td><td>31.2%</td><td>2,856</td><td>30.2%</td></tr><tr><td>Mortgage-backed securities:</td><td></td><td></td><td></td><td></td></tr><tr><td>Residential</td><td>34</td><td>0.3%</td><td>44</td><td>0.4%</td></tr><tr><td>Commercial</td><td>659</td><td>6.7%</td><td>381</td><td>4.0%</td></tr><tr><td>Asset-backed securities</td><td>68</td><td>0.7%</td><td>83</td><td>0.9%</td></tr><tr><td>Corporate debt securities</td><td>3,794</td><td>38.5%</td><td>3,580</td><td>37.9%</td></tr><tr><td>Total debt securities</td><td>$9,847</td><td>100.0%</td><td>$9,453</td><td>100.0%</td></tr></table>

Question: In the year with largest amount of Residential , what's the sum of Mortgage-backed securities? (in million)
Answer: 4088.0