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Represents the percentage of associated future global development costs from the initiation of a Phase IIb trial provided the entity elects to co-develop any compounds and/or indications.

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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License Agreements - Lilly (Details) - USD ($) $ in Thousands	1 Months Ended				3 Months Ended								12 Months Ended			133 Months Ended
	May 31, 2019	Mar. 31, 2016	Jul. 31, 2010	Dec. 31, 2009	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020
License agreements
Research and Development Expense													$ 2,215,942	$ 1,154,111	$ 1,197,957
Revenues					$ 789,509	$ 620,643	$ 688,043	$ 568,507	$ 579,389	$ 551,581	$ 529,932	$ 497,857	2,666,702	2,158,759	1,881,883
Europe
License agreements
Revenues													105,000	90,000	79,900
Product royalty revenues
License agreements
Revenues					$ 119,900	$ 98,400	$ 92,800	$ 81,800	$ 88,600	$ 80,100	$ 76,000	$ 61,600	392,966	306,337	234,780
Eli Lilly
License agreements
Upfront payment received under license agreement				$ 90,000
Revenues													30,000	0	120,000
Eli Lilly \| Non-U.S.
License agreements
Revenues													$ 110,900	80,400	40,100
Eli Lilly \| Phase IIB
License agreements
Associated future global development costs from the initiation of a Phase IIb trial, if elected to co-develop (as a percentage)			30.00%	30.00%									30.00%
Research and Development Expense													$ 0	$ 0	68,600
Eli Lilly \| Pre-specified Events \| Maximum
License agreements
Upfront and immediate milestone payment to be received under license agreement				$ 665,000
Eli Lilly \| Development Milestones
License agreements
Amount recognized and received for the achievement of a predefined milestone															20,000	$ 149,000
Eli Lilly \| Development Milestones \| Maximum
License agreements
Upfront and immediate milestone payment to be received under license agreement				150,000
Eli Lilly \| Regulatory Milestones
License agreements
Amount recognized and received for the achievement of a predefined milestone															$ 100,000	$ 265,000
Eli Lilly \| Regulatory Milestones \| JAPAN
License agreements
Amount recognized and received for the achievement of a predefined milestone													10,000
Eli Lilly \| Regulatory Milestones \| Europe
License agreements
Amount recognized and received for the achievement of a predefined milestone													$ 20,000
Eli Lilly \| Regulatory Milestones \| Maximum
License agreements
Upfront and immediate milestone payment to be received under license agreement				365,000
Eli Lilly \| Sales and Commercial Milestones \| Maximum
License agreements
Upfront and immediate milestone payment to be received under license agreement				$ 150,000
Royalty payments on future global net sales (as a percent)													20.00%
Eli Lilly \| GVHD
License agreements
Upfront payment under license agreement		$ 35,000
Additional milestone payments under the license agreement		$ 40,000
Eli Lilly \| GVHD \| Regulatory Milestones
License agreements
Milestone payment made under license agreement	$ 20,000