Fair Value (Detail) - Fair Value Measurements of Other Financial Instruments - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Assets:
Cash and due from banks	$ 114,587	$ 117,315
Interest-bearing deposits in other banks	266,615	488,947
Securities held-to-maturity	23,152	26,555
FHLB and FRB stock	39,306	37,558
Loans	7,088,085	6,664,159
Investment in BOLI	209,601	206,498
Liabilities:
Deposits	8,097,738	7,887,758
Borrowed funds	165,096	137,994
Senior and subordinated debt	201,208	200,869
Level 1
Assets:
Cash and due from banks	114,587	117,315
Liabilities:
Senior and subordinated debt	205,726	209,035
Level 1 | Carrying Amount
Assets:
Cash and due from banks	114,587	117,315
Liabilities:
Senior and subordinated debt	201,208	200,869
Level 2
Assets:
Interest-bearing deposits in other banks	266,615	488,947
Securities held-to-maturity	20,054	27,670
FHLB and FRB stock	39,306	37,558
Liabilities:
Deposits	8,093,640	7,879,413
Borrowed funds	165,096	137,994
Accrued interest payable	2,175	2,324
Level 2 | Carrying Amount
Assets:
Interest-bearing deposits in other banks	266,615	488,947
Securities held-to-maturity	23,152	26,555
FHLB and FRB stock	39,306	37,558
Liabilities:
Deposits	8,097,738	7,887,758
Borrowed funds	165,096	137,994
Accrued interest payable	2,175	2,324
Level 3
Assets:
Loans	6,959,024	6,536,248
Investment in BOLI	209,601	206,498
Accrued interest receivable	27,847	27,506
Other interest-earning assets	1,982	3,799
Level 3 | Carrying Amount
Assets:
Loans	7,091,988	6,672,611
Investment in BOLI	209,601	206,498
Accrued interest receivable	27,847	27,506
Other interest-earning assets	$ 1,982	$ 3,799