Parent Company Financial Statements - Condensed Statement of Income (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Expense
Interest on long-term borrowings	$ 248,556	$ 189,372	$ 231,017
Other expense	3,288,062	3,140,325	3,047,485
Income tax credits	(590,160)	(915,556)	(743,284)
Equity in undistributed income of subsidiaries
Net income	$ 1,918,080	$ 1,408,306	$ 1,315,114
Net income per common share
Basic	$ 12.75	$ 8.72	$ 7.80
Diluted	$ 12.74	$ 8.70	$ 7.78
Parent Company [Member]
Income
Dividends from consolidated bank subsidiaries	$ 1,250,000	$ 1,540,000	$ 1,930,000
Equity in earnings of Bayview Lending Group LLC	23,500	352	(10,752)
Other income	2,417	9,493	5,530
Total income	1,275,917	1,549,845	1,924,778
Expense
Interest on long-term borrowings	36,354	21,591	18,963
Other expense	23,894	19,636	21,361
Total expense	60,248	41,227	40,324
Income before income taxes and equity in undistributed income of subsidiaries	1,215,669	1,508,618	1,884,454
Income tax credits	8,446	26,453	17,247
Income before equity in undistributed income of subsidiaries	1,224,115	1,535,071	1,901,701
Equity in undistributed income of subsidiaries
Net income of subsidiaries	1,943,965	1,413,235	1,343,413
Less: dividends received	(1,250,000)	(1,540,000)	(1,930,000)
Equity in undistributed income of subsidiaries	693,965	(126,765)	(586,587)
Net income	$ 1,918,080	$ 1,408,306	$ 1,315,114
Net income per common share
Basic	$ 12.75	$ 8.72	$ 7.80
Diluted	$ 12.74	$ 8.70	$ 7.78