Reconciliation of Net Income to Net Income Available to Common Shareholders (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net Income (Loss) Attributable to Parent		$ 1,878	$ 1,933	$ 1,774
Dividends, Preferred Stock, Cash	[1]	(66)	(64)	(42)
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic		(1)	(6)	(10)
Net Income (Loss) Available to Common Stockholders, Basic		$ 1,811	$ 1,863	$ 1,722
Average basic common shares		498,638	514,844	527,500
Stock options		1,000	2,000	1,000
Restricted stock		3,000	4,000	4,000
Net income/(loss) per average common share - diluted		$ 3.60	$ 3.58	$ 3.23
Earnings Per Share, Basic		$ 3.63	$ 3.62	$ 3.26

[1] For the year ended December 31, 2016, dividends were $4,067 per share for both Perpetual Preferred Stock Series A and B, $5,875 per share for Perpetual Preferred Stock Series E, and $5,625 per share for Perpetual Preferred Stock Series F.For the year ended December 31, 2015, dividends were $4,056 per share for both Perpetual Preferred Stock Series A and B, $5,875 per share for Perpetual Preferred Stock Series E, and $6,219 per share for Perpetual Preferred Stock Series F.