Loans - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2015 USD ($) Contract	Dec. 31, 2014 USD ($) Contract
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Single family loans in FDIC acquired loans covered by loss share agreement	$ 170,100,000
Balances of loans due from related parties	17,400,000	$ 16,200,000
Changes in new loans	18,300,000
Repayments in affiliates loans	16,500,000
Net balance reduction in directors and affiliates loans	(600,000)
Nonaccrual loans	159,713,000	79,537,000
Troubled debt restructuring both accruing and nonaccruing	13,100,000	16,000,000
Minimum bank portfolio loan need to be reviewed	1,000,000
Loans held for sale	20,434,000	20,252,000
Real estate acquired through foreclosure	26,256,000	58,415,000
Commercial Non-Real Estate [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans	88,743,000	15,511,000
Consumer [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans	9,061,000	5,748,000
Mortgage loan in process of foreclosure	7,400,000	13,700,000
Real estate acquired through foreclosure	9,300,000	12,700,000
Residential Mortgages [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans	$ 23,799,000	$ 22,094,000
Number of TDRs subsequently defaulted | Contract	0	1
Recorded investment		$ 300,000
Loans Modified In Troubled Debt Restructure [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans	$ 8,800,000	7,000,000
Originated Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans	156,721,000	71,296,000
Originated Loans [Member] | Commercial Non-Real Estate [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans	88,743,000	$ 15,511,000
Number of TDRs subsequently defaulted | Contract		1
Recorded investment		$ 900,000
Originated Loans [Member] | Consumer [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans	9,061,000	5,574,000
Originated Loans [Member] | Residential Mortgages [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans	23,799,000	21,702,000
FDIC Acquired Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans		2,102,000
FDIC Acquired Loans [Member] | Consumer [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans		174,000
Mortgage loan in process of foreclosure	4,100,000	8,100,000
Real estate acquired through foreclosure	$ 1,600,000	8,200,000
FDIC Acquired Loans [Member] | Residential Mortgages [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans		$ 392,000
Performing [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Period for which payments of principal and interest are past due	Less than 90 days