Commitments and Contingencies - Additional Information (Detail) - Jun. 30, 2017 - Further Indication for AMR101 $ in Millions	USD ($)	GBP (£)
Marketing Approval In Europe
Commitments And Contingencies Disclosure [Line Items]
Potential aggregate stock or cash payment	$ 9.8	£ 7,500,000
Potential Marketing Approval 1
Commitments And Contingencies Disclosure [Line Items]
Potential aggregate stock or cash payment	6.5	5,000,000
Potential Marketing Approval 2
Commitments And Contingencies Disclosure [Line Items]
Potential aggregate stock or cash payment	6.5	5,000,000
Maximum
Commitments And Contingencies Disclosure [Line Items]
Potential aggregate stock or cash payment	$ 13.0	£ 10,000,000