Long-term Debt - Senior secured notes (Details) (Senior secured notes [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended			12 Months Ended		3 Months Ended
	Dec. 31, 2012	Jun. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2009	Dec. 14, 2012 Prior to December 15, 2013 [Member]	Dec. 31, 2012 Prior to December 15, 2013 [Member]	Jun. 30, 2012 Issuance of Equity [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount					$ 250.0
Debt Instrument, Discount					5
Unamortized Discount on the Senior Notes				4.1
Debt redeemed, % of principal						35.00%
Debt outstanding, % of principal						65.00%
Proceeds Used for Early Extinguishment of Debt								54.9
Extinguishment of Debt, Amount	200.0	50.0
Long-term Debt, Redemption Price, % of principal amount		109.75%				109.75%	100.00%
Non-cash Debt Extinguishment Costs			8.1
Debt Issuance Costs Incurred During Noncash or Partial Noncash Transaction			$ 35.7