Income Taxes - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($)
Schedule Of Pre Tax Income [Line Items]
Excess tax benefits on share based payments	$ 5.8
Earliest Tax Year [Member] | New York State [Member]
Schedule Of Pre Tax Income [Line Items]
Income tax year under examination	2010
Latest Tax Year [Member] | New York State [Member]
Schedule Of Pre Tax Income [Line Items]
Income tax year under examination	2012