Condensed Consolidated Statements of Changes in Equity (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Senior Preferred Stock	Preferred Stock	Common Stock	Accumulated Deficit	Accumulated Other Comprehensive Income	Treasury Stock	Transition impact, net of tax, from the adoption of the current expected credit loss standard	Transition impact, net of tax, from the adoption of the current expected credit loss standard Accumulated Deficit	Adjusted Balance	Adjusted Balance Senior Preferred Stock	Adjusted Balance Preferred Stock	Adjusted Balance Common Stock	Adjusted Balance Accumulated Deficit	Adjusted Balance Accumulated Other Comprehensive Income	Adjusted Balance Treasury Stock
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)	$ (1,139)	$ (1,139)	$ 13,469	$ 120,836	$ 19,130	$ 687	$ (119,915)	$ 131	$ (7,400)
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	4					4
Reclassification adjustment for gains included in net income, net of tax	3					3
Prior service cost and actuarial gains, net of amortization for defined benefit plans, net of tax	(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
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)
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	(11)					(11)
Reclassification adjustment for gains included in net income, net of tax	0					0
Prior service cost and actuarial gains, net of amortization for defined benefit plans, net of tax	(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
Balance (shares) at Dec. 31, 2020		1	556	1,158
Balance at Dec. 31, 2020	25,259	$ 120,836	$ 19,130	$ 687	(108,110)	116	(7,400)
Comprehensive income:
Net income	12,145				12,145
Other comprehensive income (loss), net of tax effect:
Changes in net unrealized gains on available-for-sale securities, net of tax	(4)					(4)
Reclassification adjustment for gains included in net income, net of tax	(50)					(50)
Prior service cost and actuarial gains, net of amortization for defined benefit plans, net of tax	(5)					(5)
Total comprehensive income	12,086
Balance at Jun. 30, 2021	37,345	$ 120,836	$ 19,130	$ 687	(95,965)	57	(7,400)
Balance (shares) at Jun. 30, 2021		1	556	1,158
Balance (shares) at Mar. 31, 2021		1	556	1,158
Balance at Mar. 31, 2021	30,225	$ 120,836	$ 19,130	$ 687	(103,117)	89	(7,400)
Comprehensive income:
Net income	7,152				7,152
Other comprehensive income (loss), net of tax effect:
Changes in net unrealized gains on available-for-sale securities, net of tax	2					2
Reclassification adjustment for gains included in net income, net of tax	(33)					(33)
Prior service cost and actuarial gains, net of amortization for defined benefit plans, net of tax	(1)					(1)
Total comprehensive income	7,120
Balance at Jun. 30, 2021	$ 37,345	$ 120,836	$ 19,130	$ 687	$ (95,965)	$ 57	$ (7,400)
Balance (shares) at Jun. 30, 2021		1	556	1,158