Income Taxes (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Deferred income tax benefit	$ (4,074,000)	$ (638,000)
Deferred tax liabilities	11,631,000
Provisional transition tax amount			$ 0
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Taxable income (loss)	(35,100,000)	11,800,000
Current income tax expense (benefit)	113,000	236,000
Operating loss carryforwards	279,500,000
Federal and state research and development tax credits	7,800,000
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Current income tax expense (benefit)	(125,000)	$ (131,000)
Operating loss carryforwards	$ 160,700,000