Long-term Debt - ASU 2015-03 (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Current portion long-term debt	$ 308,945	$ 272,027
Long-term debt, net of current maturities	2,261,959	1,676,776
Total long-term debt	2,570,904	1,948,803
Unamortized debt issue cost, net	(25,393)	(20,902)
Total long-term debt, net of debt issue costs	$ 2,545,511	1,927,901
Accounting Standards Update 2015-03
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Unamortized debt issue cost, net		$ (20,900)