Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule Of Pre Tax Income [Line Items]
Pre-tax income from U.S. operations		$ 165.2	$ 161.9	$ 126.4
U.S. federal tax at statutory rate		35.00%	35.00%	35.00%
Provisional tax charge recorded due to enactment of Tax Act		$ 11.7
Re-measurement of U.S. deferred tax assets		6.7
Repatriation taxes on accumulated undistributed foreign earnings		$ 5.0
Additional annual limitations		50% or greater change
Percentage of change in ownership		50.00%
Additional annual limitations period		3 years
Capital loss on the sale		$ 20.6
Capital loss carried back		$ 1.2
New York State [Member] | Earliest Tax Year [Member]
Schedule Of Pre Tax Income [Line Items]
Income tax year under examination		2010
New York State [Member] | Latest Tax Year [Member]
Schedule Of Pre Tax Income [Line Items]
Income tax year under examination		2013
Scenario Forecast [Member]
Schedule Of Pre Tax Income [Line Items]
U.S. federal tax at statutory rate	21.00%
Foreign Country [Member]
Schedule Of Pre Tax Income [Line Items]
Pre-tax income from foreign operations		$ 36.6	$ 29.7	$ 21.5
US Country [Member]
Schedule Of Pre Tax Income [Line Items]
Net operating loss carryforwards related to prior ownership change		$ 4.2
Net operating loss carryforwards, expiration date		2021