Credit Loss Reserves - Summarizes Changes in Credit Loss Reserves by Product/Class and Related Receivable Balance by Product (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012		Dec. 31, 2012
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period	$ 4,607		$ 5,952
Provision for credit losses	24		791
Charge-offs	(399)		(979)
Recoveries	73		101
Total net charge-offs	(326)		(878)
Other	8		0
Credit loss reserves at end of period	4,313		5,865
Reserve components:
Collectively evaluated for impairment	821		1,166
Individually evaluated for impairment	3,332	[1]	4,279	[1]
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell	154		411
Receivables acquired with deteriorated credit quality	6		9
Total credit loss reserves	4,313		5,865
Receivables:
Collectively evaluated for impairment	17,516		26,347
Individually evaluated for impairment	12,093	[1]	13,446	[1]
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell	2,306		6,204
Receivables acquired with deteriorated credit quality	15		40
Total receivables	31,930		46,037
First Mortgage [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period	3,867		4,089
Provision for credit losses	16		642
Charge-offs	(301)		(568)
Recoveries	29		8
Total net charge-offs	(272)		(560)
Other	8
Credit loss reserves at end of period	3,619		4,171
Reserve components:
Collectively evaluated for impairment	615		679
Individually evaluated for impairment	2,846	[1]	3,074	[1]
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell	153		410
Receivables acquired with deteriorated credit quality	5		8
Total credit loss reserves	3,619		4,171
Receivables:
Collectively evaluated for impairment	15,241		19,855
Individually evaluated for impairment	10,968	[1]	10,999	[1]
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell	2,240		6,132
Receivables acquired with deteriorated credit quality	12		35
Total receivables	28,461		37,021		29,301
Second Mortgage [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period	740		823
Provision for credit losses	40		131
Charge-offs	(98)		(190)
Recoveries	12		15
Total net charge-offs	(86)		(175)
Other	0
Credit loss reserves at end of period	694		779
Reserve components:
Collectively evaluated for impairment	206		228
Individually evaluated for impairment	486	[1]	549	[1]
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell	1		1
Receivables acquired with deteriorated credit quality	1		1
Total credit loss reserves	694		779
Receivables:
Collectively evaluated for impairment	2,275		3,037
Individually evaluated for impairment	1,125	[1]	1,108	[1]
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell	66		72
Receivables acquired with deteriorated credit quality	3		5
Total receivables	3,469		4,222		3,638
Personal non-credit card [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period	0		1,040
Provision for credit losses	(32)		18
Charge-offs	0		(221)
Recoveries	32		78
Total net charge-offs	32		(143)
Other	0
Credit loss reserves at end of period	0		915
Reserve components:
Collectively evaluated for impairment	0		259
Individually evaluated for impairment	0	[1]	656	[1]
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell	0		0
Receivables acquired with deteriorated credit quality	0		0
Total credit loss reserves	0		915
Receivables:
Collectively evaluated for impairment	0		3,455
Individually evaluated for impairment	0	[1]	1,339	[1]
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell	0		0
Receivables acquired with deteriorated credit quality	0		0
Total receivables	$ 0		$ 4,794

[1] These amounts represent TDR Loans for which we evaluate reserves using a discounted cash flow methodology. Each loan is individually identified as a TDR Loan and then grouped together with other TDR Loans with similar characteristics. The discounted cash flow impairment analysis is then applied to these groups of TDR Loans. The receivable balance above excludes TDR Loans that are carried at the lower of amortized cost or fair value of the collateral less cost to sell which totaled $1.7 billion and $3.1 billion at March 31, 2013 and 2012, respectively. The reserve component above excludes credit loss reserves for TDR Loans that are carried at the lower of amortized cost or fair value of the collateral less cost to sell which totaled $107 million and $204 million at March 31, 2013 and 2012, respectively. These credit loss reserves are reflected within receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell in the table above.