Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		35.00%
Operating Loss Carryforwards, Limitation Rate on Taxable Income		80.00%
Increase Decrease in Deferred Tax Assets Due To Change in Enacted Tax Rate		$ 6.6
Increase Decrease in Deferred Tax Liabilities Due To Change in Enacted Tax Rate		16.3
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount		$ 9.7
Scenario, Plan [Member]
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%