Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e637-108580

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669686-108580

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e681-108580

Name:	us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Accumulated Other Comprehensive Income (Changes In The Components Of AOCI) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Beginning balance			$ (156)
Other comprehensive income (loss) before reclassification			115
Amounts reclassified from AOCI			37
Total other comprehensive income (loss)	$ 70	$ (14)	152	$ (69)
Ending balance	(4)		(4)
Unrealized gains (losses) on AFS, net [Member]
Beginning balance			(39)
Other comprehensive income (loss) before reclassification			115
Amounts reclassified from AOCI			14
Total other comprehensive income (loss)			129
Ending balance	90		90
Foreign currency translation, net [Member]
Beginning balance			(7)
Other comprehensive income (loss) before reclassification			0
Amounts reclassified from AOCI			0
Total other comprehensive income (loss)			0
Ending balance	(7)		(7)
Instrument-specific credit risk of liabilities measured at fair value, net [Member]
Beginning balance			(110)
Other comprehensive income (loss) before reclassification			0
Amounts reclassified from AOCI			23
Total other comprehensive income (loss)			23
Ending balance	$ (87)		$ (87)