Note Supplemental disclosure on the consolidated statments of cash flows (Additional disclosures on cash flow information and non-cash activities) (Detail) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Cash Flow Noncash Investing And Financing Activities Disclosure Abstract
Transfers Of Loans To Other Real Estate Owned		$ 80,992	$ 93,412
Transfers Of Loans To Other Property		22,987	22,408
Total loans transferred to foreclosed assets		103,979	115,820
Financed sales of other real estate assets		10,621	11,861
Financed sales of other foreclosed assets		5,964	13,426
Total financed sales of other foreclosed and real estate assets		16,585	25,287
Transfer Of Loans Held For Sale To Portfolio Loans 1		1,705	5,947
Account receivable from sale of loans		0	0
Noncash Transfer To Securities From Loans Resulting From Securitization	[1]	454,507	594,094
Trades receivables from brokers and counterparties		999	80,125	$ 46,630
Trades Payables To Brokers And Counterparties		999	22,174
Receivables from investment maturities		270,000	0	$ 0
Recognition of mortgage servicing rights on securitizations or asset transfers		$ 7,530	$ 7,886

[1] Includes loans securitized into trading securities and subsequently sold before quarter end.