Summary of Significant Accounting Policies - Other Comprehensive Income (Loss) Net of Tax Activity (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Foreign currency translation adjustments		$ 4,177	$ (4,321)	$ (5,676)
Foreign currency realized losses reclassified into earnings			(3)	666
Change in fair value of derivative designated as cash flow hedge		441
Gain on sale of interest rate hedging agreement, net of tax(1)	[1]	(17)	2,175
Other comprehensive income (loss), net of tax	[2]	$ 4,601	$ (2,149)	$ (5,010)

[1] On December 1, 2016, the Company sold the interest rate hedge agreement. The fair value of the interest rate hedge was recorded in other comprehensive income (loss), net of tax, and will be reclassified to earnings when earnings are impacted by the cash flows of the hedged items, the interest payments on the Credit Facility or its replacement from January 31, 2018 to January 31, 2023. See additional details on the hedge agreement in Note 9—Derivative Instruments and Hedging Activities.

[2] Net of tax of $1.0 million, $2.2 million, and $1.0 million for the years ended December 31, 2017, 2016, and 2015, respectively.