Notes Payable - Additional Information (Detail)	1 Months Ended		3 Months Ended	9 Months Ended
	Feb. 28, 2017 USD ($)	Dec. 31, 2016 USD ($) PromissoryNote	Sep. 30, 2018 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	May 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Carrying value of Notes payable			$ 49,074,000	$ 49,074,000			$ 50,565,000
Net of current portion and accounts payable			15,163,000	15,163,000			9,304,000
Gain (loss) on remeasurement of embedded derivatives				3,668,000	$ (657,000)
Long-term debt			152,675,000	152,675,000			54,251,000
Andexxa | HealthCare Royalty Partners and its Affiliates (“HCR”)
Debt Instrument [Line Items]
Accrued interest			17,600,000	17,600,000			7,400,000
Net of current portion and accounts payable			6,500,000	6,500,000			0
Gain (loss) on remeasurement of embedded derivatives			$ 1,900,000	$ 4,300,000
Amount received under royalty sales agreement	$ 50,000,000
Additional amount receivable upon U.S. regulatory approval	$ 100,000,000
Effective interest rate			13.80%	13.80%
Debt instrument increase, accrued interest			$ 5,100,000	$ 10,200,000
Royalty sales agreement fee			2,000,000	2,000,000		$ 5,000,000
Additional debt issuance costs				600,000
Long-term debt			152,700,000	152,700,000			54,300,000
Outstanding debt, net of unamortized debt discount			7,000,000	7,000,000			2,300,000
Funding amount						$ 100,000,000
Andexxa | HealthCare Royalty Partners and its Affiliates (“HCR”) | Scenario Two | Maximum
Debt Instrument [Line Items]
Percentage of royalty obligated to pay of net worldwide sales	8.21%
Andexxa | HealthCare Royalty Partners and its Affiliates (“HCR”) | Scenario Two | Minimum
Debt Instrument [Line Items]
Percentage of royalty obligated to pay of net worldwide sales	3.94%
Andexxa | HealthCare Royalty Partners and its Affiliates (“HCR”) | Scenario Three
Debt Instrument [Line Items]
Percentage of royalty obligated to pay of net worldwide sales	195.00%
Andexxa | HealthCare Royalty Partners and its Affiliates (“HCR”) | Scenario Three | Maximum
Debt Instrument [Line Items]
Transaction expense	$ 290,600,000
Andexxa | HealthCare Royalty Partners and its Affiliates (“HCR”) | Scenario Three | Minimum
Debt Instrument [Line Items]
Target payment for royalty obligation	$ 150,000,000
Andexxa | Fair Value, Inputs, Level 3 | HealthCare Royalty Partners and its Affiliates (“HCR”)
Debt Instrument [Line Items]
Estimated fair value of long-term debt			161,900,000	$ 161,900,000			58,800,000
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer")
Debt Instrument [Line Items]
Debt instrument repayment terms, description				if the approval of Andexxa in the United States and EU is not achieved by January 1, 2019, we are able to reduce the repayment amount to $60.0 million if such amount is paid by December 31, 2021 and regardless of the timing of regulatory approval, we may reduce the repayment amount to $62.5 million if such amount is paid by December 31, 2023. Any unpaid amounts shall become immediately due upon: (1) a change of control of the company; (2) an event of default; and (3) termination of the agreement for breach. We have the right to prepay the repayment amount at any time without penalty.
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") | Paid by December 31, 2021
Debt Instrument [Line Items]
Repayment amount		$ 60,000,000
Repayment date		Dec. 31, 2021
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") | Paid by December 31, 2023
Debt Instrument [Line Items]
Repayment amount		$ 62,500,000
Repayment date		Dec. 31, 2023
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") | United States and EU
Debt Instrument [Line Items]
Initial regulatory approval date		Jan. 01, 2019
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") | United States and EU | Andexxa
Debt Instrument [Line Items]
Percentage of net sales to be paid in each quarter		5.00%
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") | Promissory Notes
Debt Instrument [Line Items]
Proceeds from notes payable		$ 50,000,000
Number of debt instruments | PromissoryNote		2
Promissory notes, face amount		$ 65,000,000
Promissory notes due date		2024-12
Accrued interest			6,800,000	$ 6,800,000			4,200,000
Carrying value of Notes payable			49,100,000	49,100,000			50,600,000
Net of current portion and accounts payable			3,900,000	3,900,000			0
Gain (loss) on remeasurement of embedded derivatives			200,000	(600,000)
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") | Promissory Notes | Fair Value, Inputs, Level 3
Debt Instrument [Line Items]
Estimated fair value of Notes			$ 53,200,000	$ 53,200,000			$ 55,500,000