Debt Obligations (5.5% Convert Sr Notes) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012
Debt Instrument [Line Items]
Decription of Asset exchange.	In January 2013, we entered into the Procurement Agreement with an unaffiliated third party entity, which matures on July 9, 2014. The Procurement Agreement was entered into in connection with the unaffiliated third party’s entry into a credit support arrangement with a providing bank. Pursuant to this credit support arrangement, the third party pledged cash, contributed by one of our shareholders, to secure letters of credit in the amount of $33.0 million. The letters of credit secure decommissioning obligations in connection with certain of our U.K. license agreements.
[SubordinatedDebtMember]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	10.00%
Debt Instrument Conversion Denomination	1,000
[FivePointFivePercentFixedRateDueTwoThousandAndSixteenMember] | [ConvertibleDebtMember]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	135,000,000
Debt Instrument, Interest Rate, Stated Percentage	5.50%
Debt Instrument, Convertible, Conversion Ratio	54.019
Debt Instrument, Convertible, Conversion Price	18.51