Receivables - Additional Information on Nonaccrual Receivables (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Receivables [Abstract]
Interest income that would have been recorded if the nonaccrual receivable had been current in accordance with contractual terms during the period	$ 354	$ 819	$ 1,100
Interest income that was recorded on nonaccrual receivables included in interest income on nonaccrual loans during the period	$ 114	$ 216	$ 331