Consolidated Statements of Changes in Equity - USD ($) shares in Millions, $ in Millions	Total	Senior Preferred Stock	Preferred Stock	Common Stock	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Noncontrolling Interest
Balance (shares) at Dec. 31, 2012		1	556	1,158
Balance at Dec. 31, 2012	$ 7,224	$ 117,149	$ 19,130	$ 687	$ (122,766)	$ 384	$ (7,401)	$ 41
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Change in investment in noncontrolling interest	(10)							(10)
Comprehensive income:
Net income	83,982				83,963			19
Other comprehensive income, net of tax effect:
Changes in net unrealized gains on available-for-sale securities (net of tax of $529, $389 and $151, respectively)	983					983
Reclassification adjustment for gains included in net income (net of tax of $157, $123 and $253, respectively)	(290)					(290)
Prior service cost and actuarial gains, net of amortization for defined benefit plans (net of tax of $68, $20 and $0, respectively)	126					126
Total comprehensive income	84,801
Senior preferred stock dividends	(82,452)				(82,452)
Other	28				28
Balance at Dec. 31, 2013	9,591	$ 117,149	$ 19,130	$ 687	(121,227)	1,203	(7,401)	50
Balance (shares) at Dec. 31, 2013		1	556	1,158
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Change in investment in noncontrolling interest	(11)							(11)
Comprehensive income:
Net income	14,209				14,208			1
Other comprehensive income, net of tax effect:
Changes in net unrealized gains on available-for-sale securities (net of tax of $529, $389 and $151, respectively)	722					722
Reclassification adjustment for gains included in net income (net of tax of $157, $123 and $253, respectively)	(228)					(228)
Prior service cost and actuarial gains, net of amortization for defined benefit plans (net of tax of $68, $20 and $0, respectively)	36					36
Total comprehensive income	14,739
Senior preferred stock dividends	(20,594)				(20,594)
Other	(5)				(5)
Balance at Dec. 31, 2014	3,720	$ 117,149	$ 19,130	$ 687	(127,618)	1,733	(7,401)	40
Balance (shares) at Dec. 31, 2014		1	556	1,158
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 $529, $389 and $151, respectively)	(280)					(280)
Reclassification adjustment for gains included in net income (net of tax of $157, $123 and $253, respectively)	(483)					(483)
Prior service cost and actuarial gains, net of amortization for defined benefit plans (net of tax of $68, $20 and $0, respectively)	437					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
Balance at Sep. 30, 2015	4,000
Comprehensive income:
Net income	2,467
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