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 2016-02 [Member]					$ 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
Balance at beginning of period, shares at Dec. 31, 2016		1,265	714
Balance at beginning of period at Dec. 31, 2016		$ 1,265
Balance at beginning of period at Dec. 31, 2016			$ 0	$ 18,148	1,386	(444)	$ 1,560	$ (618)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Return of capital to parent				0
Employee benefit plans				(18)
Net income (loss)	$ (179)				(179)
Cash dividends declared on preferred stock					(77)
Other comprehensive income, net of tax	13					13
Balance at end of period, shares at Dec. 31, 2017		1,265	714
Balance at end of period at Dec. 31, 2017	18,829		$ 0	18,130	1,227	(518)	1,130	$ (431)
Balance at end of period at Dec. 31, 2017	20,094	$ 1,265
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of new accounting principle in period of adoption | Accounting Standards Update 2016-02 [Member]					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
Return of capital to parent				0
Employee benefit plans				6
Net income (loss)	320				320
Cash dividends declared on preferred stock					(76)
Other comprehensive income, net of tax	152					152
Balance at end of period, shares at Dec. 31, 2018		1,265	714
Balance at end of period at Dec. 31, 2018	19,241		$ 0	18,136	1,498	(366)	$ 1,471
Balance at end of period at Dec. 31, 2018	20,506	$ 1,265
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of new accounting principle in period of adoption | Accounting Standards Update 2016-02 [Member]					27
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
Return of capital to parent				(2,400)
Employee benefit plans				0
Net income (loss)	113				113
Cash dividends declared on preferred stock					(77)
Other comprehensive income, net of tax	87					87
Balance at end of period, shares at Dec. 31, 2019		1,265	714
Balance at end of period at Dec. 31, 2019	16,991		$ 0	$ 15,736	$ 1,534	$ (279)
Balance at end of period at Dec. 31, 2019	$ 18,256	$ 1,265