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	Noncontrolling Interest
Balance (shares) at Dec. 31, 2014		1	556	1,158
Balance at Dec. 31, 2014	$ 3,720	$ 117,149	$ 19,130	$ 687	$ (127,618)	$ 1,733	$ (7,401)	$ 40
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Change in investment in noncontrolling interest	(12)							(12)
Comprehensive income:
Net income	10,955				10,954			1
Other comprehensive income, net of tax effect:
Changes in net unrealized gains on available-for-sale securities (net of tax of $151, $30 and $28, respectively)	(280)					(280)
Reclassification adjustment for gains included in net income (net of tax of $253, $316 and $139, respectively)	(483)					(483)
Prior service cost and actuarial gains, net of amortization for defined benefit plans (net of tax)	437					437
Other, net of tax	(437)
Total comprehensive income	10,629
Senior preferred stock dividends	(10,278)				(10,278)
Balance at Dec. 31, 2015	4,059	$ 117,149	$ 19,130	$ 687	(126,942)	1,407	(7,401)	29
Balance (shares) at Dec. 31, 2015		1	556	1,158
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Change in investment in noncontrolling interest	(29)							(29)
Comprehensive income:
Net income	12,313				12,313			0
Other comprehensive income, net of tax effect:
Changes in net unrealized gains on available-for-sale securities (net of tax of $151, $30 and $28, respectively)	(55)					(55)
Reclassification adjustment for gains included in net income (net of tax of $253, $316 and $139, respectively)	(587)					(587)
Other, net of tax	(6)					(6)
Total comprehensive income	11,665
Senior preferred stock dividends	(9,624)				(9,624)
Balance at Dec. 31, 2016	6,071	$ 117,149	$ 19,130	$ 687	(124,253)	759	(7,401)	0
Balance (shares) at Dec. 31, 2016		1	556	1,158
Comprehensive income:
Net income	2,463				2,463			0
Other comprehensive income, net of tax effect:
Changes in net unrealized gains on available-for-sale securities (net of tax of $151, $30 and $28, respectively)	53					53
Reclassification adjustment for gains included in net income (net of tax of $253, $316 and $139, respectively)	(259)					(259)
Other, net of tax	0
Total comprehensive income	2,257
Senior preferred stock dividends	(12,015)				(12,015)
Balance at Dec. 31, 2017	(3,686)	$ 117,149	$ 19,130	$ 687	$ (133,805)	$ 553	(7,400)	$ 0
Balance (shares) at Dec. 31, 2017		1	556	1,158
Other comprehensive income, net of tax effect:
Stockholders' Equity, Other	$ 1						$ 1