Fair Value Measurements - Carrying Values and Fair Values of Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014		Dec. 31, 2013
ASSETS
Securities available-for-sale	$ 588,488		$ 509,425
FHLB and other restricted stock	15,818		13,629
LIABILITIES
Junior subordinated debt securities	45,619		45,619
Carrying Value [Member]
ASSETS
Cash and due from banks, including interest-bearing deposits	130,235	[1]	108,356	[1]
Securities available-for-sale	588,488	[1]	509,425	[1]
Loans held for sale	3,102	[1]	2,136	[1]
Portfolio loans, net of unearned income	3,725,079	[1]	3,566,199	[1]
Bank owned life insurance	61,348	[1]	60,480	[1]
FHLB and other restricted stock	15,818	[1]	13,629	[1]
Trading securities held in a Rabbi Trust	3,117	[1]	2,864	[1]
Mortgage servicing rights	2,743	[1]	2,919	[1]
LIABILITIES
Deposits	3,865,246	[1]	3,672,308	[1]
Securities sold under repurchase agreements	25,269	[1]	33,847	[1]
Short-term borrowings	185,000	[1]	140,000	[1]
Long-term borrowings	20,636	[1]	21,810	[1]
Junior subordinated debt securities	45,619	[1]	45,619	[1]
Carrying Value [Member] | Interest Rate Swaps [Member]
ASSETS
Derivative financial assets	14,082	[1]	13,698	[1]
LIABILITIES
Derivative financial liabilities	14,050	[1]	13,647	[1]
Carrying Value [Member] | Interest Rate Lock Commitments [Member]
ASSETS
Derivative financial assets	292	[1]	85	[1]
Carrying Value [Member] | Forward Sale Contracts [Member]
ASSETS
Derivative financial assets			34	[1]
LIABILITIES
Derivative financial liabilities	59	[1]
Fair Value Measurements [Member]
ASSETS
Cash and due from banks, including interest-bearing deposits	130,235		108,356
Securities available-for-sale	588,488		509,425
Loans held for sale	3,121		2,139
Portfolio loans, net of unearned income	3,691,807		3,538,072
Bank owned life insurance	61,348		60,480
FHLB and other restricted stock	15,818		13,629
Trading securities held in a Rabbi Trust	3,117		2,864
Mortgage servicing rights	2,890		3,143
LIABILITIES
Deposits	3,867,540		3,673,624
Securities sold under repurchase agreements	25,269		33,847
Short-term borrowings	185,000		140,000
Long-term borrowings	21,779		22,924
Junior subordinated debt securities	45,619		45,619
Fair Value Measurements [Member] | Level 1 [Member]
ASSETS
Cash and due from banks, including interest-bearing deposits	130,235		108,356
Securities available-for-sale	179		202
Trading securities held in a Rabbi Trust	3,117		2,864
Fair Value Measurements [Member] | Level 2 [Member]
ASSETS
Securities available-for-sale	588,309		509,223
Bank owned life insurance	61,348		60,480
Fair Value Measurements [Member] | Level 3 [Member]
ASSETS
Loans held for sale	3,121		2,139
Portfolio loans, net of unearned income	3,691,807		3,538,072
FHLB and other restricted stock	15,818		13,629
Mortgage servicing rights	2,890		3,143
LIABILITIES
Deposits	3,867,540		3,673,624
Securities sold under repurchase agreements	25,269		33,847
Short-term borrowings	185,000		140,000
Long-term borrowings	21,779		22,924
Junior subordinated debt securities	45,619		45,619
Fair Value Measurements [Member] | Interest Rate Swaps [Member]
ASSETS
Derivative financial assets	14,082		13,698
LIABILITIES
Derivative financial liabilities	14,050		13,647
Fair Value Measurements [Member] | Interest Rate Swaps [Member] | Level 2 [Member]
ASSETS
Derivative financial assets	14,082		13,698
LIABILITIES
Derivative financial liabilities	14,050		13,647
Fair Value Measurements [Member] | Interest Rate Lock Commitments [Member]
ASSETS
Derivative financial assets	292		85
Fair Value Measurements [Member] | Interest Rate Lock Commitments [Member] | Level 2 [Member]
ASSETS
Derivative financial assets	292		85
Fair Value Measurements [Member] | Forward Sale Contracts [Member]
ASSETS
Derivative financial assets			34
LIABILITIES
Derivative financial liabilities	59
Fair Value Measurements [Member] | Forward Sale Contracts [Member] | Level 2 [Member]
ASSETS
Derivative financial assets			34
LIABILITIES
Derivative financial liabilities	$ 59

[1] As reported in the Consolidated Balance Sheets