Leases - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Lessee Lease Description [Line Items]
Operating lease, option to extend	true
Deferred rent	$ 1.6
Lease assets	$ 24.9
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherNoncurrentAssetsMember
Short-term lease liabilities	$ 8.7
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesAndOtherLiabilities
Long-term lease liabilities	$ 16.2
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent
Operating lease rent expense	$ 2.4	$ 1.8
Cash paid of measurement of operating lease liabilities	$ 2.2
Weighted average discount rate of operating leases	4.20%
Weighted average remaining operating lease term	2 years 7 months 6 days
Operating lease liabilities, lease not yet commenced	$ 4.0
Minimum [Member]
Lessee Lease Description [Line Items]
Operating lease expiration year	2019
Maximum [Member]
Lessee Lease Description [Line Items]
Operating lease expiration year	2024
Operating lease option to extend lease term	five years