Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Pre Tax Income [Line Items]
Pre-tax income from U.S. operations	$ 168.5	$ 165.2	$ 161.9
U.S. federal tax at statutory rate	21.00%	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
Reduction in provisional tax charge	$ 0.4
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	2015
Foreign Country [Member]
Schedule Of Pre Tax Income [Line Items]
Pre-tax income from foreign operations	$ 49.6	$ 36.6	$ 29.7
US Country [Member]
Schedule Of Pre Tax Income [Line Items]
Net operating loss carryforwards related to prior ownership change	$ 2.9
Net operating loss carryforwards, expiration date	2021