Revenue Recognition - Additional Information (Detail) - USD ($)	1 Months Ended				3 Months Ended		9 Months Ended
	Oct. 31, 2016	Mar. 31, 2016	Feb. 29, 2016	Jul. 31, 2014	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration and license revenue (reversal of revenue)					$ 36,799,000	$ 14,177,000	$ 87,392,000	$ 24,832,000
Costs to obtain or fulfill the contract capitalized					0		0
Contract liabilities					5,460,000		5,460,000		$ 6,335,000
Unbilled - collaboration and license revenue					3,788,000		3,788,000		9,880,000
Deferred revenue
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Contract liabilities					5,460,000		5,460,000		$ 6,335,000
2016 Agreement | BMS and Pfizer
Collaborative Arrangements and Non-collaborative 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
2016 Agreement | BMS and Pfizer | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Transaction price							12,000,000.0
Upfront payment					15,000,000.0		15,000,000.0
2016 Agreement | BMS and Pfizer | Topic 606 | Accounting Standards Update 2014-09 | Deferred revenue
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Contract liabilities					4,400,000		4,400,000
2016 Agreement | BMS and Pfizer | Minimum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of royalties entitle to receive under agreement			5.00%
2016 Agreement | BMS and Pfizer | Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of royalties entitle to receive under agreement			15.00%
2016 Agreement | Daiichi Sankyo, Inc ("Daiichi") | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements and Non-collaborative 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					6,300,000		6,300,000
Regulatory milestone payments							10,000,000.0
2016 Agreement | Daiichi Sankyo, Inc ("Daiichi") | Topic 606 | Accounting Standards Update 2014-09 | Ethnic Sensitivity Study
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Estimated variable consideration transaction price					4,300,000		4,300,000
2016 Agreement | Daiichi Sankyo, Inc ("Daiichi") | Topic 606 | Accounting Standards Update 2014-09 | Deferred revenue
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Unbilled - collaboration and license revenue					1,700,000		1,700,000
2016 Agreement | Bayer Pharma AG
Collaborative Arrangements and Non-collaborative 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
2016 Agreement | Bayer Pharma AG | Ethnic Sensitivity Study
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Reimbursement of costs and expenses percentage			33.00%
2016 Agreement | Bayer Pharma AG | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements and Non-collaborative 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					6,300,000		6,300,000
Unbilled - collaboration and license revenue					2,100,000		2,100,000
2016 Agreement | Bayer Pharma AG | Topic 606 | Accounting Standards Update 2014-09 | Ethnic Sensitivity Study
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Estimated variable consideration transaction price					4,300,000		4,300,000
2016 Agreement | Bayer Pharma AG | Minimum | Rivaroxaban
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Reimbursement of costs and expenses percentage			33.00%
2016 Agreement | Bayer Pharma AG | Maximum | Rivaroxaban
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Reimbursement of costs and expenses percentage			100.00%
2014 Agreement | Daiichi Sankyo, Inc ("Daiichi")
Collaborative Arrangements and Non-collaborative 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
2014 Agreement | Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Costs to obtain or fulfill the contract capitalized					0		0
October 2016 Agreement | Daiichi Sankyo, Inc ("Daiichi")
Collaborative Arrangements and Non-collaborative 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%
March 2016 Agreement | Daiichi Sankyo, Inc ("Daiichi") | Ethnic Sensitivity Study
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Reimbursement of costs and expenses percentage		33.00%
March 2016 Agreement | Daiichi Sankyo, Inc ("Daiichi") | Minimum | Edoxaban
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Reimbursement of costs and expenses percentage		33.00%
March 2016 Agreement | Daiichi Sankyo, Inc ("Daiichi") | Maximum | Edoxaban
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Reimbursement of costs and expenses percentage		100.00%
2014 Agreement and October 2016 Amendment | Daiichi Sankyo, Inc ("Daiichi") | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements and Non-collaborative 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
2014 Agreement and October 2016 Amendment | Daiichi Sankyo, Inc ("Daiichi") | Topic 606 | Accounting Standards Update 2014-09 | Deferred revenue
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Contract liabilities					800,000		800,000
Distribution Fees and Reserves for Cargebacks and Product Returns
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Reduction to revenue					5,600,000		11,700,000
Royalty
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration and license revenue (reversal of revenue)							0
Collaboration and license revenue
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration and license revenue (reversal of revenue)					1,056,000	$ 7,001,000	4,123,000	$ 14,785,000
Collaboration and license revenue | 2016 Agreement | BMS and Pfizer | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration and license revenue (reversal of revenue)					(100,000)		300,000
Collaboration and license revenue | 2016 Agreement | Daiichi Sankyo, Inc ("Daiichi") | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration and license revenue (reversal of revenue)					600,000		1,400,000
Collaboration and license revenue | 2016 Agreement | Bayer Pharma AG | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration and license revenue (reversal of revenue)					400,000		1,500,000
Collaboration and license revenue | 2014 Agreement | BMS and Pfizer | Maximum | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration and license revenue (reversal of revenue)							100,000
Collaboration and license revenue | 2014 Agreement | Bayer Pharma, AG ('Bayer") and Janssen Pharmaceuticals, Inc. ("Janssen") | Maximum | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration and license revenue (reversal of revenue)							100,000
Collaboration and license revenue | 2014 Agreement and October 2016 Amendment | Daiichi Sankyo, Inc ("Daiichi") | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration and license revenue (reversal of revenue)					200,000		900,000
New Drug Application | 2016 Agreement | BMS and Pfizer | Topic 606 | Accounting Standards Update 2014-09
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Estimated variable consideration transaction price							4,200,000
New Drug Application | 2016 Agreement | BMS and Pfizer | Topic 606 | Accounting Standards Update 2014-09 | Japan
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment					$ 5,000,000.0		5,000,000.0
Phase Four Clinical Trial | 2016 Agreement | BMS and Pfizer | Topic 606 | Accounting Standards Update 2014-09 | Japan
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Costs on clinical trial							600,000
Decrease in transaction price							$ 12,800,000