Subsidiary Guarantors Senior Notes (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Senior Notes (Details) [Abstract]
Face value of senior notes	$ 300.0
Interest rate of senior notes	6.625%
Portion of proceeds from senior notes used to repay outstanding term debt	200.0
Senior notes are redeemable at a premium declining from this percentage	103.313%
Percentage of original aggregate principle amount of senior notes included in repurchase price at change of control	101.00%
Event of default for senior notes - failure of other debt payment at maturity in excess of this amount	50.0
Event of default for senior notes - not discharged, bonded or insured judgment in excess of this amount	$ 50.0
Our ownership percentage of subsidiary guarantors of senior notes	100.00%