Fair Value Measurements - Contingent Consideration Liability (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2016 item	Jun. 30, 2015 USD ($)
Rollforward of contingent consideration liability level three fair value measurements
Change in fair value of contingent consideration liability during year		$ (4,910)
Contingent Consideration Liability | Significant Unobservable Inputs (Level 3)
Rollforward of contingent consideration liability level three fair value measurements
Balance at the beginning of the period		6,922
Change in fair value of contingent consideration liability during year		90
Balance at the end of the period		1,812
Additional information
Number of unobservable inputs | item	2
Minimum probability of acquired entity meeting contractual operating performance target (as a percent)	33.00%
Maximum probability of acquired entity meeting contractual operating performance target (as a percent)	100.00%
Contingent Consideration Liability | Significant Unobservable Inputs (Level 3) | Q3 Contracting
Rollforward of contingent consideration liability level three fair value measurements
Payment to Q3C sellers for meeting performance targets		(5,000)
Contingent Consideration Liability | Significant Unobservable Inputs (Level 3) | RamFab
Rollforward of contingent consideration liability level three fair value measurements
Reduction due to non-attainment of performance target - Ram Fab		$ (200)