Recently Issued and Proposed Accounting Pronouncements (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Recently Issued and Proposed Accounting Pronouncements
Reduction in debt liabilities	$ (990,480)	$ (991,918)
Accounting Standards Update 2015-03 | Adjustment
Recently Issued and Proposed Accounting Pronouncements
Reduction in debt liabilities	10,700	11,200
Accounting Standards Update 2015-03 | Adjustment | Other long-term assets
Recently Issued and Proposed Accounting Pronouncements
Reclassification of unamortized debt issuance costs	$ 10,700	$ 11,200