Reconciliation of Net Income/(Loss) to Net Income/(Loss) Available to Common Shareholders (Detail) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Net Income (Loss) Attributable to Parent	$ 1,774		$ 1,344		$ 1,958
Dividends, Preferred Stock, Cash	(42)	[1]	(37)	[1]	(12)	[1]
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic	10		10		15
Net Income (Loss) Available to Common Stockholders, Basic	$ 1,722		$ 1,297		$ 1,931
Average basic common shares	527,500		534,283		534,149
Stock options	1,000		1,000		1,000
Restricted stock	4,000		4,000		3,000
Average diluted common shares	533,391		539,093		538,061
Net income/(loss) per average common share - diluted	$ 3.23		$ 2.41		$ 3.59
Earnings Per Share, Basic	$ 3.26		$ 2.43		$ 3.62

[1] For the year ended December 31, 2014, dividends were $4,056 per share for both Perpetual Preferred Stock Series A and B, and $5,875 per share for Perpetual Preferred Stock Series E.For the year ended December 31, 2013, dividends were $4,056 per share for both Perpetual Preferred Stock Series A and B, and $5,793 per share for Perpetual Preferred Stock Series E.For the year ended December 31, 2012, dividends were $4,052 per share for both Perpetual Preferred Stock Series A and B.