Note Supplemental disclosure on the consolidated statments of cash flows (Additional disclosures on cash flow information and non-cash activities) (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Cash Flow Noncash Investing And Financing Activities Disclosure Abstract
Transfers Of Loans To Other Real Estate Owned		$ 6,254	$ 32,597
Transfers Of Loans To Other Property		9,405	8,956
Total loans transferred to foreclosed assets		15,659	41,553
Financed sales of other real estate assets		5,250	2,904
Financed sales of other foreclosed assets		4,083	3,161
Total financed sales of other foreclosed and real estate assets		9,333	6,065
Transfers from loans held-for-sale to loans held-in-portfolio		9,215	0
Noncash Transfer To Securities From Loans Resulting From Securitization	[1]	138,242	174,620
Trades receivables from brokers and counterparties		41,683	53,192	$ 7,514
Trades Payables To Brokers And Counterparties		53,973	5,128
Receivables from investment maturities		20,000	0
Recognition of mortgage servicing rights on securitizations or asset transfers		2,557	2,763
Interest capitalized on loans subject to the temporary payment moratorium		481	0
Loans booked under the GNMA buy-back option		$ 219,487	$ 2,740

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