Parent company financial statements - Condensed Statement of Income (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income
Equity in earnings of Bayview Lending Group LLC	$ (21,511)	$ (24,231)	$ (25,768)
Expense
Interest on long-term borrowings	(225,297)	(243,866)	(271,578)
Other expense	(2,509,260)	(2,478,068)	(1,914,837)
Income tax credits	(523,028)	(365,121)	(356,628)
Equity in undistributed income of subsidiaries
Net income	1,029,498	859,479	736,161
Net income per common share
Basic	$ 7.57	$ 6.37	$ 5.72
Diluted	$ 7.54	$ 6.35	$ 5.69
Parent Company [Member]
Income
Dividends from consolidated bank subsidiaries	700,000	715,000	500,000
Equity in earnings of Bayview Lending Group LLC	(21,511)	(24,231)	(25,768)
Other income	8,755	67,829	(5,435)
Total income	687,244	758,598	468,797
Expense
Interest on long-term borrowings	82,286	90,959	91,073
Other expense	19,226	87,368	7,447
Total expense	101,512	178,327	98,520
Income before income taxes and equity in undistributed income of subsidiaries	585,732	580,271	370,277
Income tax credits	43,149	50,460	48,416
Income before equity in undistributed income of subsidiaries	628,881	630,731	418,693
Equity in undistributed income of subsidiaries
Net income of subsidiaries	1,100,617	943,748	817,468
Less: dividends received	(700,000)	(715,000)	(500,000)
Equity in undistributed income of subsidiaries	400,617	228,748	317,468
Net income	$ 1,029,498	$ 859,479	$ 736,161
Net income per common share
Basic	$ 7.57	$ 6.37	$ 5.72
Diluted	$ 7.54	$ 6.35	$ 5.69