Income Taxes - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Operating Loss Carryforwards [Line Items]
Cumulative loss period	5 years
Reserve on US-based deferred tax amounts	$ 52.4
Earliest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Open tax year	2014
Latest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Open tax year	2017
State [Member]
Operating Loss Carryforwards [Line Items]
Federal income tax returns subject to examination description	State income tax returns are subject to examination for a period of three to four years after filing
Federal [Member] | Earliest Tax Year [Member] | Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards [Line Items]
Open tax year	2015
Federal [Member] | Latest Tax Year [Member] | Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards [Line Items]
Open tax year	2017