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Securities Financing Activities - Summarized Securities Financing Agreements (Details) - USD ($) $ in Millions | Dec. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Securities Financing Transaction [Line Items] |  |
Reverse repurchase agreements | $ 0 | $ 0
Total offsetting of financial assets | 0 | 0
Repurchase agreements | 0 | 0
Total offsetting of financial liabilities | 0 | 0
Counterparty And Cash Collateral Netting [Member] |  |
Securities Financing Transaction [Line Items] |  |
Reverse repurchase agreements | 0 | 0
Total offsetting of financial assets | 0 | 0
Repurchase agreements | (180) | (305)
Total offsetting of financial liabilities | (180) | (305)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] |  |
Securities Financing Transaction [Line Items] |  |
Carrying amount of assets pledged as collateral against repurchase agreements | 204 |
Liabilities associated with collateral pledged | 180 |
Gross Amount Presented in Balance Sheet [Member] |  |
Securities Financing Transaction [Line Items] |  |
Reverse repurchase agreements | 5 | 14
Total offsetting of financial assets | 5 | 14
Repurchase agreements | 187 | 319
Total offsetting of financial liabilities | 187 | 319
Netting Adjustments [Member] |  |
Securities Financing Transaction [Line Items] |  |
Reverse repurchase agreements | (5) | (14)
Total offsetting of financial assets | (5) | (14)
Repurchase agreements | (7) | (14)
Total offsetting of financial liabilities | $ (7) | $ (14)

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- Definition Sum of the carrying amounts as of the date of the latest financial statement presented of securities which are owned but transferred to another party to serve as collateral to partially or fully secure a debt obligation, repurchase agreement or other current or potential obligation, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 50 -Paragraph 1A -Subparagraph (b)(1)(i) -URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729 + Details
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- Definition Amount, after the effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=49176635&loc=d3e9760-107771 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.13(1)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(m)(1)(a)(i)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
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