Significant Accounting and Reporting Policies - Receivables (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for doubtful accounts, January 1	$ 9,625	$ 12,588	$ 14,499
Add/ (Deduct):
Provision for bad debt expense	1,588	2,709	1,554
Write-offs, net of recoveries	(81)	(3,695)	(4,045)
Currency translation and other changes	(1,784)	(365)	580
Adjustments for business dispositions	0	(1,612)	0
Adjustments for business dispositions	$ 9,348	$ 9,625	$ 12,588