Income Tax Expense (Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Federal - current	$ 153,587	$ 216,182	$ (53,273)
State and local - current	26,983	20,799	(295)
Total current	180,570	236,981	(53,568)
Federal - deferred	3,498	18,203	468
State and local - deferred	17,946	26,543	(31,757)
Total deferred	21,444	44,746	(31,289)
Income tax expense (benefit) reported in net income	202,014	281,727	(84,857)
Employee stock plans			(2,486)
Securities available-for-sale	28,495	(2,687)	131
Pension liability adjustments	2,234	2,924	1,161
Non-credit portion of OTTI losses	13	49	44
Total income taxes	$ 232,756	$ 282,013	$ (88,329)