Revenue Recognition - Additional Information (Detail) - USD ($)	1 Months Ended				3 Months Ended		6 Months Ended		12 Months Ended
	Oct. 31, 2016	Mar. 31, 2016	Feb. 29, 2016	Jul. 31, 2014	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2016	Dec. 31, 2018
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration and license revenue					$ 28,424,000	$ 4,011,000	$ 50,593,000	$ 10,655,000
Costs to obtain or fulfill the contract capitalized					0		0
Contract liabilities					5,682,000		5,682,000			$ 6,335,000
Unbilled - collaboration and license revenue					4,795,000		4,795,000			9,880,000
Deferred revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contract liabilities					5,682,000		5,682,000			$ 6,335,000
BMS and Pfizer | 2016 Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Non-refundable upfront fee									$ 15,000,000.0
Contingent payment receivable upon achievement of regulatory events									20,000,000.0
Contingent payment receivable upon achievement of annual net sales volumes									$ 70,000,000.0
BMS and Pfizer | 2016 Agreement | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price							12,500,000
Upfront payment					15,000,000.0		15,000,000.0
BMS and Pfizer | 2016 Agreement | Topic 606 | Accounting Standards Update 2014-09 | Deferred revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contract liabilities					4,700,000		4,700,000
BMS and Pfizer | 2016 Agreement | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Percentage of royalties entitle to receive under agreement									5.00%
BMS and Pfizer | 2016 Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Percentage of royalties entitle to receive under agreement									15.00%
Daiichi Sankyo, Inc ("Daiichi") | 2016 Agreement | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Costs to obtain or fulfill the contract capitalized					0		0
Transaction price							15,600,000
Upfront payment					5,000,000.0		5,000,000.0
Estimated variable consideration transaction price					6,200,000		6,200,000
Regulatory milestone payments							10,000,000.0
Daiichi Sankyo, Inc ("Daiichi") | 2016 Agreement | Topic 606 | Accounting Standards Update 2014-09 | Ethnic Sensitivity Study
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Estimated variable consideration transaction price					4,400,000		4,400,000
Daiichi Sankyo, Inc ("Daiichi") | 2016 Agreement | Topic 606 | Accounting Standards Update 2014-09 | Deferred revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Unbilled - collaboration and license revenue					2,100,000		2,100,000
Daiichi Sankyo, Inc ("Daiichi") | 2014 Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront fee				$ 15,000,000.0
Contingent payment receivable upon achievement				5,000,000.0
Milestone payments of development and regulatory event				$ 20,000,000.0
Daiichi Sankyo, Inc ("Daiichi") | October 2016 Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contingent payment receivable upon achievement of annual net sales volumes	$ 8,000,000.0
Upfront fee	15,000,000.0
Contingent payment receivable upon achievement	10,000,000.0
Milestone payments of development and regulatory event	$ 2,500,000
Percentage of consideration received under agreement	1.00%
Daiichi Sankyo, Inc ("Daiichi") | March 2016 Agreement | Ethnic Sensitivity Study
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reimbursement of costs and expenses percentage		33.00%
Daiichi Sankyo, Inc ("Daiichi") | March 2016 Agreement | Minimum | Edoxaban
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reimbursement of costs and expenses percentage		33.00%
Daiichi Sankyo, Inc ("Daiichi") | March 2016 Agreement | Maximum | Edoxaban
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reimbursement of costs and expenses percentage		100.00%
Daiichi Sankyo, Inc ("Daiichi") | 2014 and October 2016 Amendment | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price							34,000,000.0
Upfront payment					22,000,000.0		22,000,000.0
Milestones already received on achieving performance obligations							12,000,000.0
Milestone payments eligible for achievement							5,500,000
Costs to obtain or fulfill the contract					0		0
Daiichi Sankyo, Inc ("Daiichi") | 2014 and October 2016 Amendment | Topic 606 | Accounting Standards Update 2014-09 | Deferred revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contract liabilities					900,000		900,000
Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") | 2014 Agreement | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Costs to obtain or fulfill the contract capitalized					0		0
Bayer Pharma AG | 2016 Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront fee			$ 5,000,000.0
Contingent payment receivable upon achievement			10,000,000.0
Reduced contingent payment receivable upon achievement			$ 7,000,000.0
Bayer Pharma AG | 2016 Agreement | Ethnic Sensitivity Study
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reimbursement of costs and expenses percentage			33.00%
Bayer Pharma AG | 2016 Agreement | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price							15,600,000
Upfront payment					5,000,000.0		5,000,000.0
Milestone payments eligible for achievement							10,000,000.0
Costs to obtain or fulfill the contract					0		0
Estimated variable consideration transaction price					6,200,000		6,200,000
Unbilled - collaboration and license revenue					2,700,000		2,700,000
Bayer Pharma AG | 2016 Agreement | Topic 606 | Accounting Standards Update 2014-09 | Ethnic Sensitivity Study
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Estimated variable consideration transaction price					4,400,000		4,400,000
Bayer Pharma AG | 2016 Agreement | Minimum | Rivaroxaban
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reimbursement of costs and expenses percentage			33.00%
Bayer Pharma AG | 2016 Agreement | Maximum | Rivaroxaban
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reimbursement of costs and expenses percentage			100.00%
Distribution Fees and Reserves for Cargebacks and Product Returns
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reduction to revenue					(3,700,000)		(6,100,000)
Royalty
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration and license revenue							0
Collaboration and License Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration and license revenue					1,260,000	$ 1,746,000	3,067,000	$ 7,784,000
Collaboration and License Revenue | BMS and Pfizer | 2016 Agreement | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration and license revenue					200,000		400,000
Collaboration and License Revenue | BMS and Pfizer | 2014 Agreement | Maximum | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration and license revenue							100,000
Collaboration and License Revenue | Daiichi Sankyo, Inc ("Daiichi") | 2016 Agreement | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration and license revenue					200,000		800,000
Collaboration and License Revenue | Daiichi Sankyo, Inc ("Daiichi") | 2014 and October 2016 Amendment | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration and license revenue					200,000		700,000
Collaboration and License Revenue | Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") | 2014 Agreement | Maximum | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration and license revenue							100,000
Collaboration and License Revenue | Bayer Pharma AG | 2016 Agreement | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration and license revenue					600,000		1,100,000
New Drug Application | BMS and Pfizer | 2016 Agreement | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Estimated variable consideration transaction price							4,400,000
New Drug Application | BMS and Pfizer | 2016 Agreement | Topic 606 | Accounting Standards Update 2014-09 | Japan
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment					$ 5,000,000.0		5,000,000.0
Phase Four Clinical Trial | BMS and Pfizer | 2016 Agreement | Topic 606 | Accounting Standards Update 2014-09 | Japan
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Costs on clinical trial							600,000
Decrease in transaction price							$ 12,500,000