Long-term Debt - Senior secured notes (Details) (Senior secured notes [Member], USD $) In Millions, unless otherwise specified	6 Months Ended			6 Months Ended
	Jun. 30, 2012	Jun. 30, 2012 Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2011 Fair Value, Inputs, Level 2 [Member]	Jun. 30, 2012 Issuance of Equity [Member]
Debt Instrument [Line Items]
Proceeds Used for Early Extinguishment of Debt				$ 54.9
Extinguishment of Debt, Amount	50.0
Long-term Debt, Redemption Price, % of principal amount	109.75%
Non-cash Debt Extinguishment Costs	$ 1.7
Long-term Debt, Fair Value, % of par value		110.00%	108.50%