Business Segments and Geographic Information - Narrative (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) segment	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Schedule of Equity Method Investments [Line Items]
Number of reportable business segments | segment	4
Equity in earnings of affiliates, net of income tax provision	$ 2,596	$ 1,995
Investment in affiliate	$ 0		$ 0
SACS
Schedule of Equity Method Investments [Line Items]
Ownership percentage in entity	50.00%
Equity in earnings of affiliates, net of income tax provision	$ 1,400	1,600
Investment in joint venture	11,600		13,400
Geo Amey
Schedule of Equity Method Investments [Line Items]
Equity in earnings of affiliates, net of income tax provision	1,200	$ 400
Investment in affiliate	$ 6,100		$ 4,800