Business Combination (Details) - Allocation of the purchase price to the fair value of the respective assets and liabilities acquired - USD ($) $ in Thousands		3 Months Ended
	Feb. 13, 2018	Mar. 31, 2018	Mar. 31, 2017
Allocation of the purchase price to the fair value of the respective assets and liabilities acquired [Abstract]
Cash and cash equivalents	$ 25,525
Accounts receivable	14,666
Prepaid expenses	446
Property and equipment	170
Intangible assets:
Developed technology (1)	22,400
In-process research and development (2)	1,600
Total assets	64,807
Accounts payable	(3,379)
Other current liabilities	(6,351)
Liability related to sale of future royalties	(16,300)
Net assets acquired	38,777
Purchase price	(31,789)
Bargain purchase gain (3)	$ 6,988	$ 6,988