Restructuring Expenses - Schedule of Restructuring Activities and Related Reserves (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restructuring Reserve
Beginning Provision	$ 8,717	$ 8,658	$ 8,717	$ 16,675
Charges	7,200	3,080	15,620	6,492
Cost charged against liabilities (assets)		0	(1,180)	(267)
Cash paid		(6,798)	(14,468)	(15,618)
Foreign currency translation adjustment		(175)	(32)	1,435
Ending Provision		4,765	8,658	8,717
Personnel expenses
Restructuring Reserve
Beginning Provision	646	2,334	646	6,453
Charges	4,400	2,801	7,586	2,975
Cost charged against liabilities (assets)		0	(324)	0
Cash paid		(1,727)	(5,825)	(9,295)
Foreign currency translation adjustment		(9)	252	513
Ending Provision		3,400	2,334	646
Demolition and Removal costs
Restructuring Reserve
Beginning Provision	2,824	2,541	2,824	4,880
Charges		9	1,978	1,440
Cost charged against liabilities (assets)		0	(14)	(153)
Cash paid		(1,953)	(2,182)	(3,849)
Foreign currency translation adjustment		(36)	(64)	505
Ending Provision		561	2,541	2,824
Ground remediation costs
Restructuring Reserve
Beginning Provision	4,317	2,939	4,317	3,795
Charges		268	2,919	0
Cost charged against liabilities (assets)		0	(833)	0
Cash paid		(2,610)	(3,259)	0
Foreign currency translation adjustment		(109)	(206)	522
Ending Provision		488	2,939	4,317
Other
Restructuring Reserve
Beginning Provision	$ 930	844	930	1,547
Charges		2	3,137	2,076
Cost charged against liabilities (assets)		0	(8)	(114)
Cash paid		(508)	(3,202)	(2,474)
Foreign currency translation adjustment		(20)	(13)	(105)
Ending Provision		$ 317	$ 844	$ 930