Receivables - Aging Analysis of Past Due Loans (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014	Dec. 31, 2014
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	$ 21,729		$ 25,481
Threshold period for current receivable	30 days
Real estate secured [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, 30 - 89 days past due	1,405			1,737
Financing Receivable, 90 plus days past due	765			1,002
Financing Receivable, Past Due, Total	2,170			2,739
Financing Receivable, Current	19,559	[1]		19,931	[1]
Total receivables	21,729	[2]		22,670	[2]
First Lien [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, 30 - 89 days past due	1,275			1,572
Financing Receivable, 90 plus days past due	677			902
Financing Receivable, Past Due, Total	1,952			2,474
Financing Receivable, Current	17,356	[1]		17,679	[1]
Total receivables	19,308	[2]		20,153	[2]
Second Lien [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, 30 - 89 days past due	130			165
Financing Receivable, 90 plus days past due	88			100
Financing Receivable, Past Due, Total	218			265
Financing Receivable, Current	2,203	[1]		2,252	[1]
Total receivables	$ 2,421	[2]		$ 2,517	[2]

[1] Receivables less than 30 days past due are presented as current.

[2] The receivable balances included in this table reflects the principal amount outstanding on the loan net of any charge-off recorded in accordance with our existing charge-off policies and includes certain basis adjustments to the loan such as unearned income, unamortized deferred fees and costs on originated loans, purchase accounting fair value adjustments and premiums or discounts on purchased loans. However, these basis adjustments on the loans are excluded in other presentations of dollars of two-months-and-over contractual delinquency, nonaccrual receivable and nonperforming receivable account balances.