Derivative Financial Instruments - Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative liabilities, current	$ (2,596)	$ (7,314)
Derivative liabilities, noncurrent		(3,547)
Interest Rate Swap Contracts | Derivatives Designated As Hedging Instruments
Derivatives, Fair Value [Line Items]
Derivative assets (liabilities), net, total	27,626	4,760
Interest Rate Swap Contracts | Derivatives Designated As Hedging Instruments | Prepaid expenses, deferred costs, and other current assets
Derivatives, Fair Value [Line Items]
Derivative assets, current	3,217	1,154
Interest Rate Swap Contracts | Derivatives Designated As Hedging Instruments | Prepaid expenses, deferred costs, and other noncurrent assets
Derivatives, Fair Value [Line Items]
Derivative assets, noncurrent	27,005	14,467
Interest Rate Swap Contracts | Derivatives Designated As Hedging Instruments | Current Portion Of Other Long-Term Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities, current	$ (2,596)	(7,314)
Interest Rate Swap Contracts | Derivatives Designated As Hedging Instruments | Other Long-Term Liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities, noncurrent		$ (3,547)