Collaboration and License Agreements - Children's Medical Center Corporation (Details) - Children Medical Center Corporation - Collaborative Arrangement, Transaction with Party to Collaborative Arrangement $ in Millions	1 Months Ended
	Apr. 30, 2018 USD ($) shares
Collaboration and License Agreements
Shares issued (in shares) | shares	15,123
Upon achievement of first licensed target
Collaboration and License Agreements
Maximum development milestone payable	$ 7.7
Upon achievement of second licensed target
Collaboration and License Agreements
Maximum development milestone payable	3.9
Upon achievement of third licensed target
Collaboration and License Agreements
Maximum development milestone payable	$ 1.9