Goodwill and Other Intangible Assets - Gross Carrying Amount and Accumulated Amortization of Intangible Assets (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Goodwill [Line Items]
Intangible assets related to acquisition	$ 383	$ 207
Purchased Credit Card Relationship Intangible [Member]
Goodwill [Line Items]
Intangible assets related to acquisition	136
Purchased Credit Card Relationship Intangible [Member] | Elan Financial Services Inc[Member]
Goodwill [Line Items]
Intangible assets related to acquisition	135
Purchased Credit Card Relationship Intangible [Member] | New York [Member]
Goodwill [Line Items]
Intangible assets related to acquisition	1
Austin Capital Management [Member]
Goodwill [Line Items]
Gross Carrying amount	18	18
Accumulated amortization	$ 18	$ 18