Loans - Impaired Commercial Loans Considered as TDR Loans (Detail) (Commercial Loan [Member], USD $) In Millions, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Financing Receivable, Impaired [Line Items]
Amount with Impairment Reserves	$ 282		$ 250
Amount without Impairment Reserves	333		447
Total Impaired Commercial Loans	615	[1],[2],[3]	697	[1],[2],[3]
Impairment Reserve	38		96
Construction and Other Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Amount with Impairment Reserves	224		192
Amount without Impairment Reserves	241		305
Total Impaired Commercial Loans	465	[1],[2],[3]	497	[1],[2],[3]
Impairment Reserve	26		86
Business and Corporate Banking [Member]
Financing Receivable, Impaired [Line Items]
Amount with Impairment Reserves	48		57
Amount without Impairment Reserves	20		49
Total Impaired Commercial Loans	68	[1],[2],[3]	106	[1],[2],[3]
Impairment Reserve	12		10
Global Banking [Member]
Financing Receivable, Impaired [Line Items]
Amount with Impairment Reserves	0		0
Amount without Impairment Reserves	18		18
Total Impaired Commercial Loans	18	[1],[2],[3]	18	[1],[2],[3]
Impairment Reserve	0		0
Other Commercial [Member]
Financing Receivable, Impaired [Line Items]
Amount with Impairment Reserves	10		1
Amount without Impairment Reserves	54		75
Total Impaired Commercial Loans	64	[1],[2],[3]	76	[1],[2],[3]
Impairment Reserve	$ 0		$ 0

[1] Includes impaired commercial loans which are also considered TDR Loans as follows: June 30, 2013 December 31, 2012 (in millions)Construction and other real estate$435 $343Business and corporate banking27 86Other commercial28 31Total$490 $460

[2] The impaired commercial loan balances included in the table above reflect the current carrying amount of the loan and includes all basis adjustments, such as unamortized deferred fees and costs on originated loans and any premiums or discounts. The unpaid principal balance of impaired commercial loans included in the table above are as follows:June 30, 2013 December 31, 2012 (in millions)Construction and other real estate$481 $552Business and corporate banking109 157Global banking18 18Other commercial67 79Total$675 $806

[3] The reduction in impaired commercial loans for construction and other real estate loans includes the charge-off of a single loan totaling $57 million in the first quarter of 2013 which was fully reserved.