Quarterly report pursuant to Section 13 or 15(d)

Income Taxes - Additional Information (Detail)

v3.8.0.1
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%