Derivative Financial Instruments (Details Textual) (USD $)	3 Months Ended
	Mar. 31, 2012 Contract	Dec. 31, 2011
Derivative Financial Instruments (Textual) [Abstract]
Number of open forward foreign currency contracts	0
Interest rate risk	$ 100,000,000
Variable rate debt	200,000,000
Issuing date of new senior notes to paid down amount outstanding	2012/02/27
Net amount outstanding under facility agreement	140,000,000
Paid amount with proceeds from new Senior Notes	100,000,000
Remaining amount of debt	426,770,000	307,667,000
Cash paid for interest rate swaps	6,400,000
Reclassified amount from accumulated OCI associated with interest rate swaps	300,000
Unrecognized losses accumulated OCI related interest rate swaps	100,000
Facility Agreement [Member]
Derivative Financial Instruments (Textual) [Abstract]
Remaining amount of debt	$ 40,000,000	$ 141,667,000