Summary of Significant Accounting Policies (Details 8) (USD $) In Thousands, unless otherwise specified	9 Months Ended														9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014 Carrying Amount	Dec. 31, 2013 Carrying Amount	Sep. 30, 2014 Carrying Amount Senior Secured Credit Facility	Dec. 31, 2013 Carrying Amount Senior Secured Credit Facility	Sep. 30, 2014 Carrying Amount Senior Unsecured Notes [Member]	Dec. 31, 2013 Carrying Amount Senior Unsecured Notes [Member]	Sep. 30, 2014 Carrying Amount Other Long Term Obligation	Sep. 30, 2014 Estimate of Fair Value Measurement [Member]	Dec. 31, 2013 Estimate of Fair Value Measurement [Member]	Sep. 30, 2014 Estimate of Fair Value Measurement [Member] Senior Secured Credit Facility	Dec. 31, 2013 Estimate of Fair Value Measurement [Member] Senior Secured Credit Facility	Sep. 30, 2014 Estimate of Fair Value Measurement [Member] Senior Unsecured Notes [Member]	Dec. 31, 2013 Estimate of Fair Value Measurement [Member] Senior Unsecured Notes [Member]	Sep. 30, 2014 Estimate of Fair Value Measurement [Member] Other Long Term Obligation
Estimated fair values
Discount rate (as a percent)	5.00%														5.00%
Financial assets:
Cash and cash equivalents		$ 230,707	$ 292,995						$ 230,707	$ 292,995
Financial liabilities:
Long-term debt				$ 773,277	$ 748,777	$ 300,000	$ 300,000	$ 153,956			$ 769,190	$ 748,150	$ 279,000	$ 297,000	$ 153,956