Note Loans (Composition of loans held-in-portfolio-covered loans and past due status) (Detail) - USD ($) $ in Thousands	Mar. 31, 2017		Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans covered under loss-sharing agreements with the FDIC	$ 551,980		$ 572,878
Covered loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	101,240		110,336
Current	450,740		462,542
Loans covered under loss-sharing agreements with the FDIC	551,980	[1]	572,878	[2]
Covered loans | Past Due 30 To 59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	34,538		26,257
Covered loans | Past Due 60 To 89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,897		13,149
Covered loans | Past Due 90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	63,805		70,930
Covered loans | Mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	99,344		108,266
Current	436,943		448,304
Loans covered under loss-sharing agreements with the FDIC	536,287		556,570
Covered loans | Mortgages | Past Due 30 To 59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	33,374		25,506
Covered loans | Mortgages | Past Due 60 To 89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,897		12,904
Covered loans | Mortgages | Past Due 90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	63,073		69,856
Covered loans | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,896		2,070
Current	13,797		14,238
Loans covered under loss-sharing agreements with the FDIC	15,693		16,308
Covered loans | Consumer | Past Due 30 To 59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,164		751
Covered loans | Consumer | Past Due 60 To 89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0		245
Covered loans | Consumer | Past Due 90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	$ 732		$ 1,074

[1] Includes $325 million pledged to secure credit facilities at the FHLB which are not permitted to sell or repledge the collateral.

[2] Includes $337 million pledged to secure credit facilities at the FHLB which are not permitted to sell or repledge the collateral.