Bank Premises and Equipment (Detail) - USD ($) $ in Millions		Mar. 31, 2016	Dec. 31, 2015
Bank Premises and Equipment
Land and improvements	[1]	$ 682	$ 685
Buildings		1,695	1,755
Equipment		1,715	1,696
Leasehold improvements		403	403
Construction in progress		86	85
Land and improvements held for sale		41	55
Buildings held for sale		23	20
Equipment held for sale		2	3
Leasehold improvements held for sale		2	3
Accumulated depreciation and amortization		(2,464)	(2,466)
Total bank premises and equipment	[2]	$ 2,185	$ 2,239

[1] At March 31, 2016 and December 31, 2015, land and improvements included $101 and $102, respectively, associated with parcels of undeveloped land intended for future branch expansion.

[2] Includes $68 and $81 of bank premises and equipment held for sale at March 31, 2016 and December 31, 2015, respectively. Refer to Note 7.