Business Segments and Geographic Information - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) segment	Sep. 30, 2018 USD ($)	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	$ 2,228	$ 2,735	$ 6,645	$ 7,071
Investment in affiliate	0		$ 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	1,200	2,200	$ 3,800	5,900
Investment in joint venture	10,900		10,900		13,400
Geo Amey
Schedule of Equity Method Investments [Line Items]
Equity in earnings of affiliates, net of income tax provision	1,000	$ 600	2,800	$ 1,200
Investment in affiliate	$ 7,300		$ 7,300		$ 4,800