Discontinued Operations - Results from Discontinued Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Other income (expense):
Income (loss) from discontinued operations, net of applicable taxes	$ 2,246	$ (3,624)
International operations | Discontinued operations, disposed of by sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues		40,130
Cost of revenues		19,381
Amortization of acquired intangible assets		1,291
Gross profit		19,458
Operating (income) expenses:
Research and development		51
Sales and marketing		12,980
General and administrative	271	4,846
Amortization of intangible assets		622
Restructuring expenses		794
Net gain on sale of business		(7,935)
Total operating expenses	271	11,358
Operating (loss) income	(271)	8,100
Other income (expense):
Interest expense, net		(6,959)
Other income, net	7	1,883
Total other income (expense)	7	(5,076)
(Loss) income from discontinued operations before taxes	(264)	3,024
Income tax (benefit) provision	(2,510)	6,648
Income (loss) from discontinued operations, net of applicable taxes	$ 2,246	$ (3,624)