Other Liabilities - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Other Liabilities Disclosure [Abstract]
Deferred gains on sale of assets included in accrued expenses and other liabilities	$ 990		$ 990		$ 1,000
Amortization of deferred gains	$ 22	$ 22	$ 45	$ 43