Bank Premises and Equipment (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Bank Premises And Equipment [Abstract]
Land and improvements	$ 822	$ 838
Buildings	1,794	1,763
Equipment	1,650	1,581
Leasehold improvements	413	397
Construction in Progress	90	118
Accumulated depreciation and amortization	(2,302)	(2,166)
Total	$ 2,467	$ 2,531