Income Taxes - Schedule of Income Taxes Expenses Benefit Reconciliation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income taxes at statutory federal income tax rate	$ 526,730	$ 813,352	$ 720,439
Increase (decrease) in taxes:
Tax-exempt income	(26,186)	(40,778)	(35,364)
State and local income taxes, net of federal income tax effect	112,451	83,327	79,155
Qualified affordable housing project federal tax credits, net	(12,240)	(16,015)	(15,091)
Initial impact of enactment of Tax Act		85,431
Other	(10,595)	(9,761)	(5,855)
Income taxes	$ 590,160	$ 915,556	$ 743,284