Other income and other expense - Other Income and Other Expense (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Other income:
Bank owned life insurance	$ 51,199	$ 50,776	$ 50,483
Credit-related fee income	68,596	73,886	62,294
Letter of credit fees	58,496	56,247	49,762
Non-taxable gain from business combination		64,930
Other expense:
Professional services	248,544	222,122	128,629
Amortization of capitalized servicing rights	59,555	55,859	56,582
Advertising and promotion	52,388	58,312	41,869
Write-down of investment in Bayview Lending Group LLC ("BLG")		$ 79,012