Results of Reportable Segment (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended									12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011		Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Segment Reporting Information [Line Items]
Operating revenues	$ 430	$ 412	$ 410	$ 392	$ 430		$ 432	$ 411	$ 377	$ 1,644		$ 1,650		$ 1,583
Depreciation and amortization expense										195		193		190
Net (gains) write-offs										(46)		5		34
Operating Income (Loss)	112	81	56	3	80		87	53	(2)	252		218		155
Segment Interest Expense Including Net Interest On Project Debt										118		91		83
Equity in net income from unconsolidated investments										10		5		2
Assets	4,526				4,385					4,526		4,385
Payments to Acquire Productive Assets										126		118
Goodwill	249				232					249		232		230
Assets Held-for-sale [Member]
Segment Reporting Information [Line Items]
Assets	0				18					0		18
United States [Member]
Segment Reporting Information [Line Items]
Operating revenues										1,514		1,592		1,541
Assets	4,142				4,010					4,142		4,010
Other Countries [Member]
Segment Reporting Information [Line Items]
Operating revenues										130		58		42
Assets	384				357					384		357
Americas [Member]
Segment Reporting Information [Line Items]
Operating revenues										1,603		1,608		1,541
Depreciation and amortization expense										192		191		188
Net (gains) write-offs										(57)		0		11
Operating Income (Loss)										294		249		213
Segment Interest Expense Including Net Interest On Project Debt										46		38		42
Equity in net income from unconsolidated investments										0		0		0
Assets	4,028				3,955					4,028		3,955
Payments to Acquire Productive Assets										116		100
All Other [Member]
Segment Reporting Information [Line Items]
Operating revenues										41	[1]	42	[1]	42	[1]
Depreciation and amortization expense										3	[1]	2	[1]	2	[1]
Net (gains) write-offs										11	[1]	5	[1]	23	[1]
Operating Income (Loss)										(42)	[1]	(31)	[1]	(58)	[1]
Segment Interest Expense Including Net Interest On Project Debt										72	[1]	53	[1]	41	[1]
Equity in net income from unconsolidated investments										10	[1]	5	[1]	2	[1]
Assets	498				430	[1]				498		430	[1]
Payments to Acquire Productive Assets										$ 10		$ 18	[1]

[1] (1)All other is comprised of the financial results of our insurance subsidiaries’ operations and our international assets.