Business Segments - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) segment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Segment Reporting [Abstract]
Number of segments | segment	2
Segment Reporting Information [Line Items]
Property and equipment, net	$ 32,656	$ 32,681
United States
Segment Reporting Information [Line Items]
Property and equipment, net	21,200	22,100	$ 21,500
International
Segment Reporting Information [Line Items]
Property and equipment, net	$ 11,400	$ 10,600	$ 8,300