Subsequent Event (Narrative) (Details) - Subsequent Event $ in Millions	1 Months Ended
	Jul. 28, 2016 USD ($)
Jounce
Business Acquisition [Line Items]
Collaboration fee and equity purchase fee	$ 261.0
Initial term of agreement	4 years
Additional agreement term	3 years
Termination agreement, period	120 days
Program 1 | JTX-201 | Celgene
Business Acquisition [Line Items]
Profit share rate	40.00%
Program 1 | Jounce | JTX-201
Business Acquisition [Line Items]
Profit share rate	60.00%
Program 2 | Celgene
Business Acquisition [Line Items]
Profit share rate	75.00%
Program 2 | Jounce
Business Acquisition [Line Items]
Profit share rate	25.00%