Fair Values of Assets and Liabilities - Losses Recognized Related to Nonrecurring Fair Value Measurements of Individual Assets or Portfolios (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Loans	$ 31	$ 12	$ 47	$ 33
Other assets	$ 15	$ 20	$ 34	$ 59