Schedule II - 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]
Charge (Credit) to Costs and Expenses	$ 50,114	$ 45,565
Allowance for doubtful accounts receivable [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Additions for Charges to Cost and Expense	(129)	(1,311)	$ 253
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	930	2,243	1,996
Deductions, Credit to the respective receivable	(2)	(2)	(6)
Balance at End of Year	799	930	2,243
Allowance for doubtful employee advances and miscellaneous receivables [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Additions for Charges to Cost and Expense	2,184	1,294	1,125
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	681	692	402
Deductions, Credit to the respective receivable	(2,365)	(1,305)	(835)
Balance at End of Year	500	681	692
Deferred tax valuation allowance [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Additions for Charges to Cost and Expense	4,549	(6,437)	3,549
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	45,565	52,002	48,453
Deductions, Credit to the respective receivable	0	0	0
Balance at End of Year	50,114	45,565	$ 52,002
Foreign tax authority [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Charge (Credit) to Costs and Expenses	$ 1,100	$ 1,500