Debt Principal Payments by Year (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Maturities of Long-term Debt [Abstract]
2013	$ 150,000	[1]
2014	112,500
2015	172,500
2016	125,000
2017	73,500
Thereafter	640,000
Total Debt	$ 1,273,500

[1] Borrowings under the Revolving Credit Facility include $150 million classified in current liabilities due to the Company's intent to repay this amount in January 2013.