Concentrations - Portfolio Carrying Value by Geographical Area (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Entity Wide Information About Geographic Areas [Line Items]
Carrying Value	$ 4,050		$ 4,315
Total Portfolio	100.00%		100.00%
United States [Member]
Entity Wide Information About Geographic Areas [Line Items]
Carrying Value	2,841	[1]	3,186	[1]
Total Portfolio	70.10%	[1]	73.80%	[1]
Europe [Member]
Entity Wide Information About Geographic Areas [Line Items]
Carrying Value	751		693
Total Portfolio	18.60%		16.10%
Asia/Australia [Member]
Entity Wide Information About Geographic Areas [Line Items]
Carrying Value	245		241
Total Portfolio	6.00%		5.60%
Latin America [Member]
Entity Wide Information About Geographic Areas [Line Items]
Carrying Value	73		79
Total Portfolio	1.80%		1.80%
Other [Member]
Entity Wide Information About Geographic Areas [Line Items]
Carrying Value	$ 140		$ 116
Total Portfolio	3.50%		2.70%

[1] United States includes assets held for sale or re-lease that may be physically located in another region.