Nature of Operations and Basis of Presentation - Other Comprehensive Income Activity (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Foreign currency translation adjustments		$ 330	$ (165)	$ 2,802	$ (3,108)
Change in fair value of derivative designated as cash flow hedge		228		228
Other comprehensive income (loss), net of tax	[1]	$ 558	$ (165)	$ 3,030	$ (3,108)

[1] Net of tax of $0.6 million and $1.6 million for the three months ended September 30, 2017 and 2016, respectively, and $1.3 million and $3.0 million for the nine months ended September 30, 2017 and 2016, respectively.