Financial Instruments (Carrying amounts and fair value of the financial instruments) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Carrying Value Disclosures [Abstract]
Current and Long-term Debt and Capital Lease Obligations	$ 948,722	$ 947,326
Other Liabilities	25,705	24,456
Fair Value Disclosure [Abstract]
Current and Long-term Debt and Capital Lease Obligations, Fair Value Disclosure	999,411	942,895
Other Liabilities, Fair Value Disclosure	$ 24,928	$ 23,627