Fair Value Measurements - Carrying Values and Fair Values of Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
ASSETS
Securities available-for-sale	$ 551,896		$ 509,425
FHLB and other restricted stock	11,963		13,629
LIABILITIES
Junior subordinated debt securities	45,619		45,619
Carrying Value [Member]
ASSETS
Cash and due from banks, including interest-bearing deposits	185,303	[1]	108,356	[1]
Securities available-for-sale	551,896	[1]	509,425	[1]
Loans held for sale	1,133	[1]	2,136	[1]
Portfolio loans, net of unearned income	3,627,896	[1]	3,566,199	[1]
Bank owned life insurance	60,910	[1]	60,480	[1]
FHLB and other restricted stock	11,963	[1]	13,629	[1]
Trading securities held in a Rabbi Trust	2,931	[1]	2,864	[1]
Mortgage servicing rights	2,846	[1]	2,919	[1]
LIABILITIES
Deposits	3,868,281	[1]	3,672,308	[1]
Securities sold under repurchase agreements	38,434	[1]	33,847	[1]
Short-term borrowings	100,000	[1]	140,000	[1]
Long-term borrowings	21,226	[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	13,433	[1]	13,698	[1]
LIABILITIES
Derivative financial liabilities	13,390	[1]	13,647	[1]
Carrying Value [Member] | Interest Rate Lock Commitments [Member]
ASSETS
Derivative financial assets	93	[1]	85	[1]
Carrying Value [Member] | Forward Sale Contracts [Member]
ASSETS
Derivative financial assets	5	[1]	34	[1]
Fair Value Measurements [Member]
ASSETS
Cash and due from banks, including interest-bearing deposits	185,303		108,356
Securities available-for-sale	551,896		509,425
Loans held for sale	1,150		2,139
Portfolio loans, net of unearned income	3,599,775		3,538,072
Bank owned life insurance	60,910		60,480
FHLB and other restricted stock	11,963		13,629
Trading securities held in a Rabbi Trust	2,931		2,864
Mortgage servicing rights	3,030		3,143
LIABILITIES
Deposits	3,871,384		3,673,624
Securities sold under repurchase agreements	38,434		33,847
Short-term borrowings	100,000		140,000
Long-term borrowings	22,337		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	185,303		108,356
Securities available-for-sale	190		202
Trading securities held in a Rabbi Trust	2,931		2,864
Fair Value Measurements [Member] | Level 2 [Member]
ASSETS
Securities available-for-sale	551,706		509,223
Bank owned life insurance	60,910		60,480
Fair Value Measurements [Member] | Level 3 [Member]
ASSETS
Loans held for sale	1,150		2,139
Portfolio loans, net of unearned income	3,599,775		3,538,072
FHLB and other restricted stock	11,963		13,629
Mortgage servicing rights	3,030		3,143
LIABILITIES
Deposits	3,871,384		3,673,624
Securities sold under repurchase agreements	38,434		33,847
Short-term borrowings	100,000		140,000
Long-term borrowings	22,337		22,924
Junior subordinated debt securities	45,619		45,619
Fair Value Measurements [Member] | Interest Rate Swaps [Member]
ASSETS
Derivative financial assets	13,433		13,698
LIABILITIES
Derivative financial liabilities	13,390		13,647
Fair Value Measurements [Member] | Interest Rate Swaps [Member] | Level 2 [Member]
ASSETS
Derivative financial assets	13,433		13,698
LIABILITIES
Derivative financial liabilities	13,390		13,647
Fair Value Measurements [Member] | Interest Rate Lock Commitments [Member]
ASSETS
Derivative financial assets	93		85
Fair Value Measurements [Member] | Interest Rate Lock Commitments [Member] | Level 2 [Member]
ASSETS
Derivative financial assets	93		85
Fair Value Measurements [Member] | Forward Sale Contracts [Member]
ASSETS
Derivative financial assets	5		34
Fair Value Measurements [Member] | Forward Sale Contracts [Member] | Level 2 [Member]
ASSETS
Derivative financial assets	$ 5		$ 34

[1] As reported in the Consolidated Balance Sheets