Debt Obligations (Narrative) (Details) (USD $)	6 Months Ended			6 Months Ended	3 Months Ended	6 Months Ended			6 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010	Jun. 30, 2010 Parent Company [Member]	Mar. 31, 2010 7.875% Notes Due 2020 [Member]	Jun. 30, 2011 7.875% Notes Due 2020 [Member]	Dec. 31, 2010 7.875% Notes Due 2020 [Member]	Dec. 31, 2010 Credit Facility [Member]	Jun. 30, 2011 2017 Term Loan [Member]	Dec. 31, 2010 2017 Term Loan [Member]	Jun. 30, 2011 2015 Revolver [Member]	Dec. 31, 2010 2015 Revolver [Member]	Jun. 30, 2011 2017 Notes [Member]
Term Loan								$ 850,000,000	$ 666,000,000	$ 768,000,000
Line of credit facility												300,000,000
Interest rate of basis points	100
Loss on debt loss on debt extinguishment	(2,000,000)					(9,000,000)
Notes payable					300,000,000	300,000,000	300,000,000						400,000,000
Proceeds from issuance of long-term debt obligations	0	1,144,000,000		1,144,000,000	292,000,000
Debt instrument maturity date						2020			2017		2015
Write-off of deferred debt issuance cost	0	80,000,000				80,000,000
Penalty for the early extinguishment of debt	(2,000,000)					(9,000,000)
Principal payment									102,000,000
Voluntary payment									98,000,000
Short-term borrowings	0		0
Debt instrument interest rate percentage						7.875%							8.75%
Weighted average interest rate on total debt	6.00%		6.40%
Debt instrument issued percent of par						99.50%			99.50%
Percentage of principal to be paid quarterly									1.00%
Term loan issued									850,000,000
Total principal amount	1,366,000,000		1,468,000,000
Amendment Principal amount									$ 700,000,000