Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for doubtful accounts receivable
Movement in Valuation Allowances and Reserves
Balance at Beginning of Year	$ 799	$ 930	$ 2,243
Additions	724	(129)	(1,311)
Deductions	(24)	(2)	(2)
Balance at End of Year	1,499	799	930
Allowance for doubtful employee advances and miscellaneous receivables
Movement in Valuation Allowances and Reserves
Balance at Beginning of Year	500	681	692
Additions	1,665	2,184	1,294
Deductions	(1,873)	(2,365)	(1,305)
Balance at End of Year	292	500	681
Deferred tax valuation allowance
Movement in Valuation Allowances and Reserves
Balance at Beginning of Year	50,114	45,565	52,002
Additions	(15,338)	4,549	(6,437)
Deductions	0	0	0
Balance at End of Year	$ 34,776	$ 50,114	$ 45,565