Credit Loss Reserves - Analysis of Credit Loss Reserves (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended	12 Months Ended					3 Months Ended		6 Months Ended	12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010	Dec. 31, 2012 Personal non-credit card [Member]	Sep. 30, 2012 Personal non-credit card [Member]	Jun. 30, 2012 Personal non-credit card [Member]	Dec. 31, 2012 Personal non-credit card [Member]		Dec. 31, 2011 Personal non-credit card [Member]		Dec. 31, 2010 Personal non-credit card [Member]	Dec. 31, 2011 TDR [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period		$ 5,512	$ 5,952		$ 5,512		$ 7,275			$ 1,040	$ 1,040		$ 1,325		$ 1,848
Provision for credit losses			2,224	[1],[2]	4,418	[3]	5,346				15	[2]	433	[3]	1,431	925
Net charge-offs:
Charge-offs			(3,021)		(4,481)		(7,596)				(389)		(1,127)		(2,329)
Recoveries			417		503		487				299		409		375
Total net charge-offs			(2,604)		(3,978)		(7,109)				(90)		(718)		(1,954)
Reserves on receivables transferred to held for sale	0		(965)		0		0
Credit loss reserves at end of period	5,952		4,607		5,952		5,512	0			0		1,040		1,325
Provision for credit losses related to the lower of amortized cost or fair value attributable to credit for personal non-credit card receivables											112
Loss emergence period									12 months	7 months
Increase in credit loss reserve resulting from increased loss emergence period	$ 40	$ (925)						$ 350

[1] Provision for credit losses during 2012 includes $112 million related to the portion of the lower of amortized cost or fair value adjustment that was attributable to credit for personal non-credit card receivables transferred to held for sale during the second quarter of 2012. See Note 7, “Receivables Held for Sale,” for additional information. This amount was recorded as a provision for credit losses and included in the total of reserves on receivables transferred to held for sale. There was no lower of cost or fair value adjustment allocated to credit for the real estate secured receivables as these receivables were previously carried at the lower of amortized cost or fair value of the collateral less cost to sell prior to the transfer of the loans to held for sale.

[2] Provision for credit losses during 2012 includes $112 million related to the portion of the lower of amortized cost or fair value that was attributable to credit for personal non-credit card receivables transferred to held for sale during the second quarter of 2012. See Note 7, “Receivables Held for Sale,” for additional information. This amount was recorded as a provision for credit losses and included in the total of reserves on receivables transferred to held for sale. There was no lower of cost or fair value adjustment allocated to credit for the real estate secured receivables as these receivables were previously carried at the lower of amortized cost or fair value of the collateral less cost to sell prior to the transfer of the loans to held for sale.

[3] Provision for credit losses during 2011 included approximately $925 million related to the adoption of new accounting guidance for TDR Loans in the third quarter of 2011 as discussed above.