Condensed Consolidated Statement of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Shares	Common Shares Subscribed	Additional Paid in Capital	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment to adopt ASU 2016-09	$ 0			$ 122		$ (122)
Beginning balance (in shares) at Mar. 31, 2017	60,275,757	60,275,757
Beginning balance at Mar. 31, 2017	$ 166,776	$ 1	$ (1)	251,733	$ 140	(85,097)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued to settle the warrant liability to Takeda (in shares)		4,432
Shares issued to settle the Takeda warrant liability	58	$ 0		58
Share-based compensation expense (in shares)		564,111
Share-based compensation expense	7,519	$ 0		7,519
Capital contribution — share-based compensation	724			724
Unrealized loss foreign currency translation adjustment	(231)				(231)
Stock option exercises (in shares)		6,734
Stock option exercises	16			16
Shares issued to NovaQuest, net of underwriting discounts and commissions and offering expenses of $0.1 million (in shares)		138,361
Shares issued to NovaQuest, net of underwriting discounts and commissions and offering expenses of $0.1 million	1,857	$ 0		1,857
Warrants issued to Hercules with long-term debt	481			481
Net loss	$ (95,002)					(95,002)
Ending balance (in shares) at Dec. 31, 2017	60,989,395	60,989,395
Ending balance at Dec. 31, 2017	$ 82,198	$ 1	$ (1)	$ 262,510	$ (91)	$ (180,221)