Accounts Payable & Other Current Liabilities - Summary of Accounts Payable and Other Current Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Payables and Accruals [Abstract]
Accounts payable	$ 3,180		$ 2,068
Accrued expenses and other liabilities:
Employee benefits and compensation related accruals	940	[1]	2,257	[1]
General and administrative related accruals	1,252		731
Research and development related accruals	4,149		3,280
Accrued income taxes	12,331	[2]	0	[2]
Accounts payable and other accrued liabilities	$ 21,852		$ 8,336

[1] Comprised of accrued bonus, accrued vacation, and liabilities under the Company’s employee stock purchase plan.

[2] Accrued income taxes are the result of the tax gain from the IP Assignment and are expected to be substantially offset by current year losses. Refer to Note 9 for a description of the tax impact of the IP Assignment.