Annual Future Minimum Payments under Capital Leases and Noncancelable Operating Leases (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014
Bank Premises Equipment [Abstract]
2015	$ 92
2016	87
2017	79
2018	76
2019	69
Thereafter	294
Total minimum lease payments	697
2015	11
2016	9
2017	5
2018	5
2019	5
Thereafter	2
Total minimum lease payments	37
Amounts representing interest	9
Present value of net minimum lease payments	$ 28