Significant Accounting Policies (Policies)	6 Months Ended
Significant Accounting Policies (Policies)	Jun. 30, 2018
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Basis of Presentation	Basis of Presentation The accompanying unaudited consolidated financial statements have been prepared in accordance with the instructions to Form 10-Q and Article 10 of Regulation S-X and, accordingly, do not include all of the information and disclosures required by accounting principles generally accepted in the United States of America (“GAAP”) for annual periods. These statements should be read in conjunction with the consolidated financial statements and notes thereto included in the Annual Report on Form 10-K for the year ended December 31, 2017. The accompanying consolidated financial statements have not been audited by an independent registered public accounting firm in accordance with the standards of the Public Company Accounting Oversight Board (U.S.), but in the opinion of management such financial statements include all adjustments, consisting only of normal recurring adjustments, necessary for the fair statement of the Company’s consolidated financial position and results of operations. All material intercompany balances and transactions have been eliminated. The preparation of financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. As additional information becomes available or actual amounts become determinable, the recorded estimates are revised and reflected in operating results. The results of operations for the three and six months ended June 30, 2018 may not be indicative of the results that may be expected for the year ending December 31, 2018. The December 31, 2017 consolidated balance sheet was derived from audited financial statements, but does not include all disclosures required by GAAP for annual periods. Certain amounts have been reclassified in the prior year’s financial statements to conform to the current presentation. This includes a change in the classification of certain cash receipts and cash payments on the Company’s consolidated statement of cash flows as required under Accounting Standards Update (“ASU”) 2016-15, “Statement of Cash Flows (Topic 230)”. This classification change affected “Interest paid, net of interest converted to principal”, in operating cash flows, and “Principal paydowns of investment agreements” and “Principal paydowns of medium-term notes”, in financing cash flows, on the Company’s consolidated statement of cash flows for the prior period. In addition, the Company revised disclosures for the three and six months ended June 30, 2017 to correct an error related to VIE notes for which the fair value option was elected. Refer to the “Fair Value Option” section of “Note 6: Fair Value of Financial Instruments” for additional information about this disclosure revision. Such reclassifications and revisions did not materially impact total revenues, expenses, assets, liabilities, shareholders’ equity, operating cash flows, investing cash flows, or financing cash flows for all periods presented.
Recently Adopted Accounting Standards	Recently Adopted Accounting Standards Revenue from Contracts with Customers (Topic 606) (ASU 2014-09) and Deferral of the Effective Date (ASU 2015-14) In May of 2014, the Financial Accounting Standards Board (“FASB”) issued ASU 2014-09, “Revenue from Contracts with Customers (Topic 606).” ASU 2014-09 amends the accounting guidance for recognizing revenue for the transfer of goods or services from contracts with customers unless those contracts are within the scope of other accounting standards. ASU 2014-09 does not apply to financial guarantee insurance contracts within the scope of Topic 944, “Financial Services — Insurance.” In August of 2015, the FASB issued ASU 2015-14, “Revenue from Contracts with Customers (Topic 606) — Deferral of the Effective Date.” ASU 2015-14 defers the effective date of ASU 2014-09 to interim and annual periods beginning January 1, 2018, and is applied on a retrospective or modified retrospective basis. The Company adopted ASU 2014-09 in the first quarter of 2018 and the adoption of ASU 2014-09 did not affect the Company’s consolidated financial statements. Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities (ASU 2016-01) In January of 2016, the FASB issued ASU 2016-01, “Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities.” ASU 2016-01 requires certain equity investments other than those accounted for under the equity method of accounting or result in consolidation of the investee to be measured at fair value with changes in fair value recognized in net income, and permits an entity to measure equity investments that do not have readily determinable fair values at cost less any impairment plus or minus adjustments for certain changes in observable prices. An entity is also required to evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale (“AFS”) debt securities in combination with the entity’s other deferred tax assets. ASU 2016-01 requires an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability that results from a change in the instrument-specific credit risk for financial liabilities that the entity has elected to measure at fair value in accordance with the fair value option for financial instruments. ASU 2016-01 was effective for interim and annual periods beginning January 1, 2018. As such, the Company reclassed a loss of $162 million from retained earnings to accumulated other comprehensive income (“AOCI”) related to the instrument-specific credit risk portion of financial liabilities measured at fair value in accordance with the fair value option. In addition, the Company reclassed net unrealized gains of $2 million from AOCI to retained earnings related to equity investments. As of June 30, 2018 and December 31, 2017, the Company had a full valuation allowance against its deferred tax asset. Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (ASU 2018-02) In February of 2018, the FASB issued ASU 2018-02, “Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income.” ASU 2018-02 permits, but does not require, the reclassification of the income tax effects of the Tax Cuts and Jobs Act (the “Act”) from AOCI to retained earnings. ASU 2018-02 is effective for interim and annual periods beginning after December 15, 2018. Early adoption of ASU 2018-02 is permitted and is applied in the period of adoption or retroactively to each period in which the effect of the change in the U.S. federal corporate income tax rate in the Act is recognized. The Company adopted ASU 2018-02 in the first quarter of 2018. As such, the Company reclassed income taxes of $3 million from AOCI to retained earnings. The Company’s accounting policy related to releasing income tax effects that are lodged in AOCI is on a portfolio approach basis. The Company has not adopted any other new accounting pronouncements that had a material impact on its consolidated financial statements.
New Accounting Pronouncements Not Yet Adopted	Recent Accounting Developments Leases (Topic 842) (ASU 2016-02) In February of 2016, the FASB issued ASU 2016-02, “Leases (Topic 842)”, that amends the accounting guidance for leasing transactions. ASU 2016-02 requires a lessee to classify lease contracts as finance or operating leases, and to recognize assets and liabilities for the rights and obligations created by leasing transactions with lease terms more than twelve months. ASU 2016-02 substantially retains the criteria for classifying leasing transactions as finance or operating leases. For finance leases, a lessee recognizes a right-of-use asset and a lease liability initially measured at the present value of the lease payments, and recognizes interest expense on the lease liability separately from the amortization of the right-of-use asset. For operating leases, a lessee recognizes a right-of-use asset and a lease liability initially measured at the present value of the lease payments, and recognizes lease expense on a straight-line basis. ASU 2016-02 is effective for interim and annual periods beginning January 1, 2019 with early adoption permitted, and is applied on a modified retrospective basis. The adoption of ASU 2016-02 is not expected to materially impact the Company’s consolidated financial statements. Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13) In June of 2016, the FASB issued ASU 2016-13, “Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” ASU 2016-13 requires financing receivables and other financial assets measured at amortized cost to be presented at the net amount expected to be collected by recording an allowance for credit losses with changes in the allowance recorded as credit loss expense or reversal of credit loss expense based on management’s current estimate of expected credit losses each period. ASU 2016-13 does not apply to credit losses on financial guarantee insurance contracts within the scope of Topic 944, “Financial Services-Insurance.” ASU 2016-13 also requires impairment relating to credit losses on AFS debt securities to be presented through an allowance for credit losses with changes in the allowance recorded in the period of the change as credit loss expense or reversal of credit loss expense. Any impairment amount not recorded through an allowance for credit losses on AFS debt securities is recorded through other comprehensive income. ASU 2016-13 is effective for interim and annual periods beginning January 1, 2020 with early adoption permitted beginning January 1, 2019. ASU 2016-13 is applied on a modified retrospective basis except that prospective application is applied to AFS debt securities with other-than-temporary impairments (“OTTI”) recognized before the date of adoption. The Company is evaluating the impact of adopting ASU 2016-13.