Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Estimated Fair Values of Financial Instruments (Detail)

v3.2.0.727
Fair Value Measurements - Estimated Fair Values of Financial Instruments (Detail) - USD ($)
$ in Thousands
Jun. 30, 2015
Dec. 31, 2014
Dec. 31, 2013
Financial assets:      
Securities available for sale $ 728,683 $ 1,060,717  
Accrued interest receivable 8,133 9,749  
Investment in FRB stock 13,517 12,273  
Financial liabilities:      
Noninterest-bearing deposits 1,061,823 1,022,972  
Interest-bearing deposits 2,377,958 2,533,774  
Accrued interest payable 3,443 3,450  
Carrying Amount [Member]      
Financial assets:      
Cash and cash equivalents 153,231 158,320  
Securities available for sale 728,683 1,060,717  
Loans receivable, net of allowance for loan losses 2,826,086 2,735,832  
Loans held for sale 4,158 5,451  
Accrued interest receivable 8,133 9,749  
Servicing assets 13,125 13,773  
Investment in FHLB stock 16,385 17,580  
Investment in FRB stock 13,517 12,273  
Financial liabilities:      
Noninterest-bearing deposits 1,061,823 1,022,972  
Interest-bearing deposits 2,377,958 2,533,774  
Servicing liabilities 5,368 5,971  
Borrowings 18,623 168,544  
Accrued interest payable 3,443 3,450  
Off-balance sheet items:      
Commitments to extend credit 244,766 309,584  
Standby letters of credit 5,426 8,982  
Fair Value [Member] | Fair Value, Inputs, Level 1 [Member]      
Financial assets:      
Cash and cash equivalents 153,231 158,320  
Securities available for sale 22,965 23,056  
Loans receivable, net of allowance for loan losses 0 0  
Loans held for sale 0 0  
Accrued interest receivable 8,133 9,749  
Servicing assets 0 0  
Investment in FHLB stock 0 0  
Investment in FRB stock 0 0  
Financial liabilities:      
Noninterest-bearing deposits 0 0  
Interest-bearing deposits 0 0  
Servicing liabilities 0 0  
Borrowings 0 0  
Accrued interest payable 3,443 3,450  
Off-balance sheet items:      
Commitments to extend credit 0 0  
Standby letters of credit 0 0  
Fair Value [Member] | Fair Value, Inputs, Level 2 [Member]      
Financial assets:      
Cash and cash equivalents 0 0  
Securities available for sale 705,718 1,036,538  
Loans receivable, net of allowance for loan losses 0 0  
Loans held for sale 4,158 5,451  
Accrued interest receivable 0 0  
Servicing assets 0 0  
Investment in FHLB stock 16,385 17,580  
Investment in FRB stock 13,517 12,273  
Financial liabilities:      
Noninterest-bearing deposits 1,061,823 1,022,972  
Interest-bearing deposits 0 0  
Servicing liabilities 0 0  
Borrowings 0 0  
Accrued interest payable 0 0  
Off-balance sheet items:      
Commitments to extend credit 0 0  
Standby letters of credit 0 0  
Fair Value [Member] | Fair Value, Inputs, Level 3 [Member]      
Financial assets:      
Cash and cash equivalents 0 0  
Securities available for sale 0 1,123  
Loans receivable, net of allowance for loan losses 2,829,963 2,738,401  
Loans held for sale 0 0  
Accrued interest receivable 0 0  
Servicing assets 13,125 13,773  
Investment in FHLB stock 0 0  
Investment in FRB stock 0 0  
Financial liabilities:      
Noninterest-bearing deposits 0 0  
Interest-bearing deposits 2,361,096 2,528,304  
Servicing liabilities 5,368 5,971  
Borrowings 18,623 168,544  
Accrued interest payable 0 0  
Off-balance sheet items:      
Commitments to extend credit 244,766 309,584  
Standby letters of credit 5,426 8,982  
U.S. government agency securities [Member]      
Financial assets:      
Securities available for sale 62,661 128,207  
U.S. government agency securities [Member] | Carrying Amount [Member]      
Off-balance sheet items:      
Fair value reclassification from Level 1 to Level 2   128,200  
U.S. government agency securities [Member] | Carrying Amount [Member] | Fair Value, Inputs, Level 1 [Member]      
Financial assets:      
Securities available for sale     $ 128,400
U.S. government agency securities [Member] | Carrying Amount [Member] | Fair Value, Inputs, Level 2 [Member]      
Financial assets:      
Securities available for sale     $ 931,200
Other securities [Member]      
Financial assets:      
Securities available for sale $ 22,803 22,893  
Other securities [Member] | Carrying Amount [Member]      
Off-balance sheet items:      
Fair value reclassification from Level 2 to Level 1   $ 22,900