Income Taxes - Reconciliation of Income Tax to Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income tax at 34% federal statutory rate	$ (42,846)	$ (23,675)	$ (19,586)
State taxes, net of federal benefit	(19)	(65)	(691)
Change in valuation allowance	(11,208)	16,024	(14,042)
U.S. statutory tax rate change	36,085	0	0
Valuation allowance adjustment for continuing operations	0	0	15,498
Permanent interest disallowed	(150)	(1,832)	375
Foreign rate change - Impact on Deferred Taxes	1,619	521	(1,993)
Other permanent differences	5,774	1,307	114
Research and development tax credits	(274)	(145)	(1,060)
State tax rate benefit	56	578	2,181
Foreign rate differential	10,636	6,122	2,550
Credits and other	327	217	753
Provision for income tax benefit (expense)	$ 0	$ (948)	$ (15,901)
Federal statutory rate (percent)	34.00%	34.00%	34.00%