Supplemental Statements of Cash Flows Disclosures Supplemental Statements of Cash Flows Disclosures (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Supplemental Statements of Cash Flow Disclosures [Abstract]
Interest on long-term debt and borrowing under the revolving credit facility	$ 48,664	$ 47,783	$ 46,836
Income taxes paid (refund), net	(6,260)	7,343	8,596
Grants of restricted shares of common stock	3,268	2,098	1,592
Issuance of performance shares	628	663	0
Acquisition of treasury stock for options exercised	$ 500	$ 0	$ 0