Income Taxes - Components of Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current
Federal	$ 408,428	$ 363,043	$ 428,750
State and local	113,706	94,714	95,426
Total current	522,134	457,757	524,176
Deferred
Federal	(12,780)	367,308	147,662
State and local	28,637	33,482	26,351
Total deferred	15,857	400,790	174,013
Amortization of investments in qualified affordable housing projects	52,169	57,009	45,095
Income taxes	$ 590,160	$ 915,556	$ 743,284