Derivative Financial Instruments - Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Derivative liabilities, current	$ (9,252)	$ (16,533)
Derivative liabilities, noncurrent	(9,449)	(14,456)
Interest Rate Swap Contracts [Member] | Derivatives Designated As Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Derivative assets (liabilities), net, total	(4,126)	(16,852)
Interest Rate Swap Contracts [Member] | Derivatives Designated As Hedging Instruments [Member] | Prepaid Expenses Deferred Costs And Other Current Assets Caption [Member]
Derivatives, Fair Value [Line Items]
Derivative assets, current	260
Interest Rate Swap Contracts [Member] | Derivatives Designated As Hedging Instruments [Member] | Prepaid Expenses Deferred Costs And Other Noncurrent Assets Caption [Member]
Derivatives, Fair Value [Line Items]
Derivative assets, noncurrent	14,315	14,137
Interest Rate Swap Contracts [Member] | Derivatives Designated As Hedging Instruments [Member] | Current Portion Of Other Long-Term Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liabilities, current	(9,252)	(16,533)
Interest Rate Swap Contracts [Member] | Derivatives Designated As Hedging Instruments [Member] | Other Long-Term Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liabilities, noncurrent	$ (9,449)	$ (14,456)