CONSOLIDATED STATEMENT OF CHANGES IN EQUITY - USD ($) $ in Millions		Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	As Previously Reported [Member] Retained Earnings [Member]	As Previously Reported [Member] Accumulated Other Comprehensive Loss [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of new accounting principle in period of adoption | Accounting Standards Update 2016-01, Equity Investments Previously Classified as Available-for-sale [Member]						$ 0	$ 0
Cumulative effect of new accounting principle in period of adoption | Accounting Standards Update 2016-01, Equity Investments Previously Measured at Cost [Member]						0
Cumulative effect of new accounting principle in period of adoption | Accounting Standards Update 2018-02 [Member]						0	0
Cumulative effect of new accounting principle in period of adoption | Accounting Standards Update 2016-01, Fair Value Option [Member]						0	0
Balance at beginning of period at Dec. 31, 2015			$ 1,265
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred stock issuance			1,265
Preferred stock redemption			1,265
Balance at end of period at Dec. 31, 2016		$ 20,355	$ 1,265
Balance at beginning of period at Dec. 31, 2015				$ 0	$ 18,169	1,498	(407)	$ 1,498
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee benefit plans					(21)
Net income (loss)		129				129
Cash dividends declared on preferred stock						(67)
Other comprehensive income (loss), net of tax		(211)					(211)
Balance at end of period at Dec. 31, 2016		19,090		$ 0	18,148	1,386	(444)	1,560	$ (618)
Balance at beginning of period (shares) at Dec. 31, 2015			21,447,500	714
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Number of shares of preferred stock issued to parent (shares)			1,265
Number of shares of preferred stock redeemed (shares)			(21,447,500)
Balance at end of period (shares) at Dec. 31, 2016			1,265	714
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of new accounting principle in period of adoption	[1]	0
Cumulative effect of new accounting principle in period of adoption | Accounting Standards Update 2016-01, Equity Investments Previously Classified as Available-for-sale [Member]						0	0
Cumulative effect of new accounting principle in period of adoption | Accounting Standards Update 2016-01, Equity Investments Previously Measured at Cost [Member]						0
Cumulative effect of new accounting principle in period of adoption | Accounting Standards Update 2018-02 [Member]						0	0
Cumulative effect of new accounting principle in period of adoption | Accounting Standards Update 2016-01, Fair Value Option [Member]						(174)	174
Preferred stock issuance			$ 0
Preferred stock redemption			0
Balance at end of period at Dec. 31, 2017		20,094	$ 1,265
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee benefit plans					(18)
Net income (loss)		(179)				(179)
Cash dividends declared on preferred stock						(77)
Other comprehensive income (loss), net of tax		13					13
Balance at end of period at Dec. 31, 2017		18,829		$ 0	18,130	1,227	(518)	$ 1,130	$ (431)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Number of shares of preferred stock issued to parent (shares)			0
Number of shares of preferred stock redeemed (shares)			0
Balance at end of period (shares) at Dec. 31, 2017			1,265	714
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of new accounting principle in period of adoption	[1]	0
Cumulative effect of new accounting principle in period of adoption | Accounting Standards Update 2016-01, Equity Investments Previously Classified as Available-for-sale [Member]						(4)	4
Cumulative effect of new accounting principle in period of adoption | Accounting Standards Update 2016-01, Equity Investments Previously Measured at Cost [Member]						10
Cumulative effect of new accounting principle in period of adoption | Accounting Standards Update 2018-02 [Member]						91	(91)
Cumulative effect of new accounting principle in period of adoption | Accounting Standards Update 2016-01, Fair Value Option [Member]						0	0
Preferred stock issuance			$ 0
Preferred stock redemption			0
Balance at end of period at Dec. 31, 2018		20,506	$ 1,265
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee benefit plans					6
Net income (loss)		320				320
Cash dividends declared on preferred stock						(76)
Other comprehensive income (loss), net of tax		152					152
Balance at end of period at Dec. 31, 2018		$ 19,241		$ 0	$ 18,136	$ 1,471	$ (366)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Number of shares of preferred stock issued to parent (shares)			0
Number of shares of preferred stock redeemed (shares)			0
Balance at end of period (shares) at Dec. 31, 2018			1,265	714

[1] See Note 2, "Summary of Significant Accounting Polices and New Accounting Pronouncements," for additional discussion.