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 as of January 1, 2020, adjusted	Balance as of January 1, 2020, adjusted Senior Preferred Stock	Balance as of January 1, 2020, adjusted Preferred Stock	Balance as of January 1, 2020, adjusted Common Stock	Balance as of January 1, 2020, adjusted Accumulated Deficit	Balance as of January 1, 2020, adjusted Accumulated Other Comprehensive Income	Balance as of January 1, 2020, adjusted Treasury Stock	Cumulative Effect, Period of Adoption, Adjustment [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Accumulated Deficit
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	(5,601)				(5,601)
Comprehensive income:
Net income	5,832				5,832
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)	17					17
Reclassification adjustment for gains included in net income (net of tax of $- and $12, respectively)	(118)					(118)
Prior service cost and actuarial gains, net of amortization for defined benefit plans (net of tax of $1 and $1, respectively)	(5)					(5)
Total comprehensive income	5,726
Balance at Jun. 30, 2019	6,365	$ 120,836	$ 19,130	$ 687	(127,104)	216	(7,400)
Balance (shares) at Jun. 30, 2019		1	556	1,158
Other comprehensive income (loss), net of tax effect:
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax	(5)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax	31
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Plan Amendments, Tax Effect	1
Balance (shares) at Mar. 31, 2019		1	556	1,158
Balance at Mar. 31, 2019	5,361	$ 120,836	$ 19,130	$ 687	(128,175)	283	(7,400)
Increase (Decrease) in Stockholders' Equity [Rollforward]
Senior preferred stock dividends paid	(2,361)				(2,361)
Comprehensive income:
Net income	3,432				3,432
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)	9					9
Reclassification adjustment for gains included in net income (net of tax of $- and $12, respectively)	(74)					(74)
Prior service cost and actuarial gains, net of amortization for defined benefit plans (net of tax of $1 and $1, respectively)	(2)					(2)
Total comprehensive income	3,365
Balance at Jun. 30, 2019	6,365	$ 120,836	$ 19,130	$ 687	(127,104)	216	(7,400)
Balance (shares) at Jun. 30, 2019		1	556	1,158
Other comprehensive income (loss), net of tax effect:
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax	(3)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax	19
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Plan Amendments, Tax Effect	0
Accumulated deficit	(118,776)
Balance (shares) at Dec. 31, 2019		1	556	1,158					1	556	1,158
Balance at Dec. 31, 2019	14,608	$ 120,836	$ 19,130	$ 687	(118,776)	131	(7,400)	$ 13,469	$ 120,836	$ 19,130	$ 687	$ (119,915)	$ 131	$ (7,400)	$ (1,139)	$ (1,139)
Increase (Decrease) in Stockholders' Equity [Rollforward]
Senior preferred stock dividends paid	0				0
Comprehensive income:
Net income	3,006				3,006
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)	4					4
Reclassification adjustment for gains included in net income (net of tax of $- and $12, respectively)	3					3
Prior service cost and actuarial gains, net of amortization for defined benefit plans (net of tax of $1 and $1, respectively)	(5)					(5)
Total comprehensive income	3,008
Balance at Jun. 30, 2020	16,477	$ 120,836	$ 19,130	$ 687	(116,909)	133	(7,400)
Balance (shares) at Jun. 30, 2020		1	556	1,158
Other comprehensive income (loss), net of tax effect:
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax	1
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax	1
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Plan Amendments, Tax Effect	1
Balance (shares) at Mar. 31, 2020		1	556	1,158
Balance at Mar. 31, 2020	13,945	$ 120,836	$ 19,130	$ 687	(119,454)	146	(7,400)
Increase (Decrease) in Stockholders' Equity [Rollforward]
Senior preferred stock dividends paid	0				0
Comprehensive income:
Net income	2,545				2,545
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)	(11)					(11)
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)	(2)					(2)
Total comprehensive income	2,532
Balance at Jun. 30, 2020	16,477	$ 120,836	$ 19,130	$ 687	$ (116,909)	$ 133	$ (7,400)
Balance (shares) at Jun. 30, 2020		1	556	1,158
Other comprehensive income (loss), net of tax effect:
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax	(3)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Plan Amendments, Tax Effect	0
Accumulated deficit	$ (116,909)