Derivatives - Effect On Condensed Consolidated Statements of Operations (Details) - Interest rate swap contract - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivatives Designated as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Fair value of liability derivatives	$ 372	$ (38)
Derivatives Designated as Hedging Instruments | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in other comprehensive income before reclassifications	80	(450)	$ 0
Derivatives Designated as Hedging Instruments | Cash Flow Hedging | Interest expense
Derivative Instruments, Gain (Loss) [Line Items]
Loss reclassified from accumulated other comprehensive income to earnings for the effective portion	(207)	(626)	0
Derivatives Designated as Hedging Instruments | Cash Flow Hedging | Income tax expense
Derivative Instruments, Gain (Loss) [Line Items]
Income tax benefit	47	200	0
Not Designated as Hedging Instrument | Cash Flow Hedging | Income tax expense
Derivative Instruments, Gain (Loss) [Line Items]
Income tax benefit	86	0	0
Not Designated as Hedging Instrument | Cash Flow Hedging | Other, net
Derivative Instruments, Gain (Loss) [Line Items]
Loss recognized in earnings	(382)	0	$ 0
Accrued liabilities | Derivatives Designated as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Fair value of liability derivatives	$ 0	$ (38)