Condensed Consolidated Statements of Changes in Equity (Deficit) - USD ($) shares in Millions, $ in Millions	Total	Senior Preferred Stock	Preferred Stock	Common Stock	Accumulated Deficit	Accumulated Other Comprehensive Income	Treasury Stock
Balance (shares) at Dec. 31, 2018		1	556	1,158
Balance at Dec. 31, 2018	$ 6,240	$ 120,836	$ 19,130	$ 687	$ (127,335)	$ 322	$ (7,400)
Increase (Decrease) in Stockholders' Equity [Rollforward]
Senior preferred stock dividends paid	(3,240)				(3,240)
Comprehensive income:
Net income	2,400				2,400
Other comprehensive income (loss), net of tax effect:
Changes in net unrealized gains on available-for-sale securities (net of tax of $5 and $2, respectively)	8					8
Reclassification adjustment for gains included in net income (net of tax of $- and $12, respectively)	(44)					(44)
Prior service cost and actuarial gains, net of amortization for defined benefit plans (net of tax of $1 and $1, respectively)	(3)					(3)
Total comprehensive income	2,361
Balance at Mar. 31, 2019	5,361	$ 120,836	$ 19,130	$ 687	(128,175)	283	(7,400)
Balance (shares) at Mar. 31, 2019		1	556	1,158
Balance (shares) at Dec. 31, 2019		1	556	1,158
Balance at Dec. 31, 2019	14,608	$ 120,836	$ 19,130	$ 687	(118,776)	131	(7,400)
Increase (Decrease) in Stockholders' Equity [Rollforward]
Senior preferred stock dividends paid	0				0
Comprehensive income:
Net income	461				461
Other comprehensive income (loss), net of tax effect:
Changes in net unrealized gains on available-for-sale securities (net of tax of $5 and $2, respectively)	18					18
Reclassification adjustment for gains included in net income (net of tax of $- and $12, respectively)	0					0
Prior service cost and actuarial gains, net of amortization for defined benefit plans (net of tax of $1 and $1, respectively)	(3)					(3)
Total comprehensive income	476
Balance at Mar. 31, 2020	$ 13,945	$ 120,836	$ 19,130	$ 687	$ (119,454)	$ 146	$ (7,400)
Balance (shares) at Mar. 31, 2020		1	556	1,158