Asset Acquisitions and Contingent Consideration - Additional Information (Details) - USD ($)								1 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 21, 2018	Jun. 30, 2018	Jan. 31, 2018	Jan. 04, 2018	Oct. 31, 2017	Oct. 02, 2017	May 31, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jun. 24, 2018
Business Acquisition [Line Items]
In process research and development									$ 8,261,000	$ 2,000,000	$ 49,659,000
GB001
Business Acquisition [Line Items]
In process research and development											19,148,000
GB004
Business Acquisition [Line Items]
In process research and development											20,000,000
GB1275
Business Acquisition [Line Items]
In process research and development									$ 7,500,000	1,000,000	$ 7,500,000
Pulmokine, Inc. | License Agreement | GB002
Business Acquisition [Line Items]
Product license term							10 years
Upfront payment						$ 5,500,000
Milestones accrued										0
Pulmokine, Inc. | License Agreement | GB002 | Maximum
Business Acquisition [Line Items]
Development and regulatory milestone payments, payable							$ 63,000,000
Commercial milestone payments, payable							45,000,000
Sales milestone payments, payable							$ 190,000,000
AA Biopharma Inc. | GB001
Business Acquisition [Line Items]
In process research and development				$ 19,300,000
AA Biopharma Inc. | GB001 | Common Stock
Business Acquisition [Line Items]
Business acquisition, aggregate number of shares issued					1,101,278
AA Biopharma Inc. | GB001 | Series Seed Convertible Preferred Stock
Business Acquisition [Line Items]
Business acquisition, aggregate number of shares issued					20,000,000
Aerpio Pharmaceuticals, Inc. | License Agreement | GB004
Business Acquisition [Line Items]
Milestones accrued										0
Upfront payment, purchase consideration paid			$ 20,000,000
Aerpio Pharmaceuticals, Inc. | License Agreement | GB004 | Maximum
Business Acquisition [Line Items]
Development and regulatory milestone payments, payable												$ 55,000,000
Commercial milestone payments, payable												85,000,000
Sales milestone payments, payable												$ 260,000,000
Adhaere Pharmaceuticals, Inc. | GB1275
Business Acquisition [Line Items]
Milestones accrued										$ 0
In process research and development	$ 7,500,000
Upfront payment, purchase consideration paid		$ 7,500,000
Milestones payment								$ 1,000,000
Adhaere Pharmaceuticals, Inc. | GB1275 | Maximum
Business Acquisition [Line Items]
Regulatory, development and sales milestone payments payable		$ 62,000,000