Debt Obligations (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Schedule of principal payments of debt obligations
Repurchase Amount	$ 109,724
Principal	106,215
Loss	3,264
Deferred Financing Amortization	152
2011 3.75% Notes [Member]
Schedule of principal payments of debt obligations
Repurchase Amount	59,835
Principal	59,835
Loss	0
Deferred Financing Amortization	0
Debt instrument stated interest rate	3.875%
2012 5.750% Notes [Member]
Schedule of principal payments of debt obligations
Repurchase Amount	24,749
Principal	23,709
Loss	868
Deferred Financing Amortization	32
Debt instrument stated interest rate	5.75%
2015 7.500% Notes [Member]
Schedule of principal payments of debt obligations
Repurchase Amount	25,140
Principal	22,671
Loss	2,396
Deferred Financing Amortization	$ 120
Debt instrument stated interest rate	7.50%