Summary of Significant Accounting Policies - Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
New Accounting Pronouncement, Early Adoption
Other long-term assets	$ 452,305	$ 289,745
Long-term debt	3,655,200	4,331,840
Deferred income taxes		118,230
Accrued liabilities	686,613	728,004
Deferred income taxes	29,326	443,003
Simplifying the Presentation of Debt Issuance Costs | Adjustments for New Accounting Principle, Early Adoption
New Accounting Pronouncement, Early Adoption
Other long-term assets	(18,000)
Long-term debt		$ (17,000)
Balance Sheet Classification of Deferred Taxes | Adjustments for New Accounting Principle, Early Adoption
New Accounting Pronouncement, Early Adoption
Other long-term assets	40,000
Deferred income taxes	(40,000)
Accrued liabilities	(3,700)
Deferred income taxes	$ 3,700