Loans - Impaired Commercial Loans Considered as TDR Loans (Detail) (Commercial Loans [Member], USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
Amount with Impairment Reserves	$ 41		$ 165
Amount without Impairment Reserves	208		316
Total Impaired Commercial Loans	249	[1],[2]	481	[1],[2]
Impairment Reserve	10		40
Construction and Other Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Amount with Impairment Reserves	12		122
Amount without Impairment Reserves	190		211
Total Impaired Commercial Loans	202	[1],[2]	333	[1],[2]
Impairment Reserve	2		32
Business and Corporate Banking [Member]
Financing Receivable, Impaired [Line Items]
Amount with Impairment Reserves	27		28
Amount without Impairment Reserves	10		12
Total Impaired Commercial Loans	37	[1],[2]	40	[1],[2]
Impairment Reserve	7		3
Global Banking [Member]
Financing Receivable, Impaired [Line Items]
Amount with Impairment Reserves	0		14
Amount without Impairment Reserves	0		51
Total Impaired Commercial Loans	0	[1],[2]	65	[1],[2]
Impairment Reserve	0		5
Other Commercial [Member]
Financing Receivable, Impaired [Line Items]
Amount with Impairment Reserves	2		1
Amount without Impairment Reserves	8		42
Total Impaired Commercial Loans	10	[1],[2]	43	[1],[2]
Impairment Reserve	$ 1		$ 0

[1] 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 partial charge-offs, unamortized deferred fees and costs on originated loans and any premiums or discounts. The following table reflects the unpaid principal balance of impaired commercial loans included in the table above:September 30, 2014 December 31, 2013 (in millions)Construction and other real estate$220 $380Business and corporate banking78 91Global banking— 123Other commercial10 47Total$308 $641

[2] Includes impaired commercial loans that are also considered TDR Loans which totaled $229 million and $389 million at September 30, 2014 and December 31, 2013, respectively.