Revenue Recognition - Effect on Financial Statements (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Selling, general and administrative expenses	$ 14,748	$ 15,469
Other current assets	2,508		$ 4,098	$ 4,335
Intangible, equity method investment and other assets, net	20,779		20,792	20,949
Accumulated deficit	(11,570)		$ (11,731)	(11,337)
Deferred income tax liability, net	12,309			12,886
Income tax provision (benefit)	62	(1,191)
Net income (loss)	161	$ (1,787)
Calculated under Revenue Guidance in Effect before Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Selling, general and administrative expenses	14,807
Other current assets	2,745			4,335
Intangible, equity method investment and other assets, net	20,877			20,949
Accumulated deficit	(11,921)			(11,337)
Deferred income tax liability, net	12,325
Income tax provision (benefit)	46
Net income (loss)	118
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Selling, general and administrative expenses	(59)
Other current assets	(237)			(237)
Intangible, equity method investment and other assets, net	(98)			(157)
Accumulated deficit	(351)			$ (394)
Deferred income tax liability, net	(16)
Income tax provision (benefit)	16
Net income (loss)	$ 43