Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Movement in Valuation Allowances and Reserves [Roll Forward]
Allowance for doubtful accounts receivable, period start	$ 19,140	$ 20,546	$ 22,079
Additions-charged to expense	6,556	8,209	11,156
Amounts written off	(6,839)	(7,862)	(10,573)
Other (primarily changes in foreign currency exchange rates)	(488)	(1,753)	(2,116)
Allowance for doubtful accounts receivable, period end	$ 18,369	$ 19,140	$ 20,546