Accounts Payable and Accrued Expenses - Summary of Current Portion of Earnout Liabilities and Long term Portion of Earnout Liability (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition Contingent Consideration [Line Items]
Earnout accrued at beginning of period	$ 24,213	$ 32,670
Fair value adjustment	(6,610)	4,218	$ 11,222
Compensation expense adjustment	1,240	1,213
Foreign currency translation adjustment	825	(1,346)
Exchange of earnout for accounts receivable		(3,272)
Payment	(15,193)	(9,270)
Total earnout liability at end of period	4,475	24,213	32,670
Less: current portion of earnout	(2,989)	(13,527)
Balance of long term portion of earnout recorded in other liabilities at end of period	1,486	10,686
Energy Segment [Member]
Business Acquisition Contingent Consideration [Line Items]
Earnout accrued at beginning of period	24,213	30,403
Fair value adjustment	(6,610)	6,485
Compensation expense adjustment	1,240	1,213
Foreign currency translation adjustment	825	(1,346)
Exchange of earnout for accounts receivable		(3,272)
Payment	(15,193)	(9,270)
Total earnout liability at end of period	4,475	24,213	30,403
Less: current portion of earnout	(2,989)	(13,527)
Balance of long term portion of earnout recorded in other liabilities at end of period	$ 1,486	10,686
Environmental Segment [Member]
Business Acquisition Contingent Consideration [Line Items]
Earnout accrued at beginning of period		2,267
Fair value adjustment		$ (2,267)
Total earnout liability at end of period			$ 2,267