Note Loans (Composition of loans held-in-portfolio-covered loans and past due status) (Detail) - USD ($) $ in Thousands	Jun. 30, 2017		Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans covered under loss-sharing agreements with the FDIC	$ 536,341		$ 572,878
Covered loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	94,661		110,336
Current	441,680		462,542
Loans covered under loss-sharing agreements with the FDIC	536,341	[1]	572,878	[2]
Covered loans | Past Due 30 To 59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	25,156		26,257
Covered loans | Past Due 60 To 89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	12,575		13,149
Covered loans | Past Due 90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	56,930		70,930
Covered loans | Mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	92,855		108,266
Current	428,211		448,304
Loans covered under loss-sharing agreements with the FDIC	521,066		556,570
Covered loans | Mortgages | Past Due 30 To 59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	24,506		25,506
Covered loans | Mortgages | Past Due 60 To 89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	12,270		12,904
Covered loans | Mortgages | Past Due 90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	56,079		69,856
Covered loans | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,806		2,070
Current	13,469		14,238
Loans covered under loss-sharing agreements with the FDIC	15,275		16,308
Covered loans | Consumer | Past Due 30 To 59 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	650		751
Covered loans | Consumer | Past Due 60 To 89 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	305		245
Covered loans | Consumer | Past Due 90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	$ 851		$ 1,074

[1] Includes $314 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.