Schedule II - Valuation and Qualifying Accounts (Details) - Allowance for Doubtful Accounts - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance		$ 6,700	$ 6,400	$ 6,200
Net bad debt expenses	[1]	2,900	800	0
Additions (deductions)	[2]	(2,000)	(500)
Additions (deductions)	[2]			200
Ending Balance		$ 7,600	$ 6,700	$ 6,400

[1] Includes effects of changes in foreign exchange rates.

[2] Uncollectible accounts written off, net of recoveries. Also includes effects of changes in foreign exchange rates.