Reconciliation of Net Income/(Loss) to Net Income/(Loss) Available to Common Shareholders (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net Income (Loss) Attributable to Parent	$ 492	$ 483	$ 939	$ 912
Dividends, Preferred Stock, Cash	(17)	(15)	(33)	(32)	[1]
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic	0	(1)	0	(3)
Net Income (Loss) Available to Common Stockholders, Basic	$ 475	$ 467	$ 906	$ 877
Average basic common shares	501	517	503	519
Stock options	2	1	2	2
Restricted stock	3	4	3	4
Weighted Average Number of Shares Outstanding, Diluted	506	522	508	525
Net income/(loss) per average common share - diluted	$ 0.94	$ 0.89	$ 1.78	$ 1.67
Earnings Per Share, Basic	$ 0.95	$ 0.90	$ 1.80	$ 1.69

[1] For the six months ended June 30, 2016, dividends were $2,033 per share for both Perpetual Preferred Stock Series A and B, $2,938 per share for Perpetual Preferred Stock Series E, and $2,813 per share for Perpetual Preferred Stock Series F.For the six months ended June 30, 2015, dividends were $2,022 per share for both Perpetual Preferred Stock Series A and B, $2,938 per share for Perpetual Preferred Stock Series E, and $3,406 per share for Perpetual Preferred Stock Series F.