Subsequent Events (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended		12 Months Ended
	Jul. 18, 2019	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Subsequent Event [Line Items]
Annual revenues of acquired company		$ 642,099	$ 634,360	$ 1,264,330	$ 1,246,684
Velcora Holding AB
Subsequent Event [Line Items]
Annual revenues of acquired company						$ 40,000
Subsequent Event | Velcora Holding AB
Subsequent Event [Line Items]
Aggregate purchase price, cash paid	$ 87,300
Assumed debt	$ 49,900