Extinguishment of Senior Notes (Details) (USD $)	6 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011 23.3 Millions Senior Notes [Member]	Jun. 30, 2011 23.9 Millions Senior Notes [Member]
Extinguishment of Debt [Line Items]
Redeemed principle amount of senior notes	$ 61,800,000	$ 23,300,000	$ 25,900,000
Total consideration on redemption of senior notes	62,700,000	23,900,000	26,600,000
Accrued interest on redemption	1,800,000	231,000	309,000
Loss on extinguishment of debt	1,500,000	948,000	1,100,000
Unamortized debt issuance costs	$ 594,000	$ 283,000	$ 318,000
Extinguishment of Senior Notes (Textual) [Abstract]
Stated interest rate of Senior Notes redeemed	8.625%
Senior notes due date	2014