Business Combination - Narrative (Details) - USD ($) $ in Thousands		1 Months Ended	12 Months Ended
	Sep. 11, 2017	Oct. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2017
Business Acquisition [Line Items]
Purchase price, net of cash acquired			$ 59,798	$ 0	$ 0
Goodwill			117,435	$ 82,554
Lightning Diversion Systems, Inc.
Business Acquisition [Line Items]
Equity interest acquired	100.00%					100.00%
Purchase price, net of cash acquired	$ 60,000
Payments to acquire business	61,400	$ 600
Gross purchase price	62,021
Intangible assets	22,400
Goodwill	$ 34,881
Acquisition related costs			$ 300