Fair Value Measurements - Carrying Values and Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
ASSETS
Securities available-for-sale, at fair value	$ 660,963	$ 640,273
FHLB and other restricted stock	23,032	15,135
LIABILITIES
Junior subordinated debt securities	45,619	45,619	$ 45,619
Carrying Value
ASSETS
Cash and due from banks, including interest-bearing deposits	99,399	109,580
Securities available-for-sale, at fair value	660,963	640,273
Loans held for sale	35,321	2,970
Portfolio loans, net of unearned income	5,027,612	3,868,746
Bank owned life insurance	70,175	62,252
FHLB and other restricted stock	23,032	15,135
Trading securities held in a Rabbi Trust	4,021	3,456
Mortgage servicing rights	3,237	2,817
LIABILITIES
Deposits	4,876,611	3,908,842
Securities sold under repurchase agreements	62,086	30,605
Short-term borrowings	356,000	290,000
Long-term borrowings	117,043	19,442
Junior subordinated debt securities	45,619	45,619
Carrying Value | Interest Rate Swap
ASSETS
Derivative financial assets	11,295	12,981
LIABILITIES
Derivative financial liabilities	11,276	12,953
Carrying Value | Interest Rate Lock Commitments
ASSETS
Derivative financial assets	261	235
Carrying Value | Forward Sale Contracts
LIABILITIES
Derivative financial liabilities	5	57
Fair Value Measurements
ASSETS
Cash and due from banks, including interest-bearing deposits	99,399	109,580
Securities available-for-sale, at fair value	660,963	640,273
Loans held for sale	35,500	2,991
Portfolio loans, net of unearned income	5,001,004	3,827,634
Bank owned life insurance	70,175	62,252
FHLB and other restricted stock	23,032	15,135
Trading securities held in a Rabbi Trust	4,021	3,456
Mortgage servicing rights	3,396	2,934
LIABILITIES
Deposits	4,881,718	3,910,342
Securities sold under repurchase agreements	62,086	30,605
Short-term borrowings	356,000	290,000
Long-term borrowings	117,859	20,462
Junior subordinated debt securities	45,619	45,619
Fair Value Measurements | Level 1
ASSETS
Cash and due from banks, including interest-bearing deposits	99,399	109,580
Securities available-for-sale, at fair value		178
Trading securities held in a Rabbi Trust	4,021	3,456
Fair Value Measurements | Level 2
ASSETS
Securities available-for-sale, at fair value	660,963	640,095
Bank owned life insurance	70,175	62,252
Fair Value Measurements | Level 3
ASSETS
Loans held for sale	35,500	2,991
Portfolio loans, net of unearned income	5,001,004	3,827,634
FHLB and other restricted stock	23,032	15,135
Mortgage servicing rights	3,396	2,934
LIABILITIES
Deposits	4,881,718	3,910,342
Securities sold under repurchase agreements	62,086	30,605
Short-term borrowings	356,000	290,000
Long-term borrowings	117,859	20,462
Junior subordinated debt securities	45,619	45,619
Fair Value Measurements | Interest Rate Swap
ASSETS
Derivative financial assets	11,295	12,981
LIABILITIES
Derivative financial liabilities	11,276	12,953
Fair Value Measurements | Interest Rate Swap | Level 2
ASSETS
Derivative financial assets	11,295	12,981
LIABILITIES
Derivative financial liabilities	11,276	12,953
Fair Value Measurements | Interest Rate Lock Commitments
ASSETS
Derivative financial assets	261	235
Fair Value Measurements | Interest Rate Lock Commitments | Level 2
ASSETS
Derivative financial assets	261	235
Fair Value Measurements | Forward Sale Contracts
LIABILITIES
Derivative financial liabilities	5	57
Fair Value Measurements | Forward Sale Contracts | Level 2
LIABILITIES
Derivative financial liabilities	$ 5	$ 57