Lease Obligations - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) ft²	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)	Oct. 14, 2019 ft²
Lessee Lease Description [Line Items]
Right-of-use assets	$ 38.9		$ 39.8
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent		us-gaap:OtherAssetsNoncurrent
Lease liability, current	$ 4.6		$ 4.4
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent		us-gaap:AccruedLiabilitiesCurrent
Lease liability, noncurrent	$ 45.2		$ 46.5
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent		us-gaap:OtherLiabilitiesNoncurrent
Rent expense	$ 1.6	$ 1.6
Weighted-average discount rate	7.11%
Weighted-average remaining lease term	10 years 3 months 10 days
Dublin Office [Member]
Lessee Lease Description [Line Items]
Approximate square feet of office space | ft²	18,900			63,000