Condensed Financial Information - Parent Company Only - Schedule of Condensed Cash Flow Statement (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net income	$ 21,189	$ 20,872	$ 18,882
Adjustments to reconcile net income to net cash provided by operating activities:
Other-than-temporary impairment on equity securities		13	16
Net gain on sales of investment securities	(3,389)	(305)	(1,417)
Loss on termination of interest rate swap	1,866
Bank owned life insurance (income) expense	(2,968)	(2,670)	(1,668)
Depreciation of premises and equipment	2,927	2,925	2,591
Stock based compensation	978	1,267	888
Contributions to pension and other postretirement benefit plans	(2,243)	(8,215)	(2,325)
Decrease (increase) in other assets	(2,850)	8,065	692
(Decrease) increase in other liabilities	142	2,180	2,846
Net cash provided by operating activities	32,806	37,139	42,698
Cash flows from investing activities:
Proceeds from bank owned life insurance	3,540	2,415	791
Net cash provided by (used in) investing activities	21,595	(58,181)	(57,788)
Cash flows from financing activities:
Payment for repurchase of trust preferred securities	(20,619)
Purchases of treasury stock	(12,012)	(2,319)	(1,928)
Stock issued under dividend reinvestment and employee stock purchase plans	2,422	2,515	2,287
Cash dividends paid	(10,029)	(16,755)	(13,367)
Net cash (used in) provided by financing activities	(120,154)	79,584	43,323
Net (decrease) increase in cash and due from financial institutions	(65,753)	58,542	28,233
Cash and due from banks at beginning of year	98,399	39,857	11,624
Cash and due from banks at end of year	32,646	98,399	39,857
Cash paid during the year for:
Interest	5,997	8,701	11,202
Income tax, net of refunds received	5,352	1,819	4,626
Parent Company [Member]
Cash flows from operating activities:
Net income	21,189	20,872	18,882
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed net income of subsidiaries	(3,923)	150	(6,581)
Other-than-temporary impairment on equity securities		13	16
Net gain on sales of investment securities	(644)	(70)	(58)
Loss on termination of interest rate swap	1,866
Bank owned life insurance (income) expense	(1,070)	(255)	18
Depreciation of premises and equipment	344	358	341
Stock based compensation	978	1,267	888
Contributions to pension and other postretirement benefit plans	(2,243)	(8,215)	(2,325)
Decrease (increase) in other assets	671	6,270	(1,746)
(Decrease) increase in other liabilities	(2,426)	2,451	2,613
Net cash provided by operating activities	14,742	22,841	12,048
Cash flows from investing activities:
Proceeds from sales of securities	1,244	2,666	7,127
Purchases of investment securities			(2,525)
Liquidation of subsidiary, net of cash acquired	15,011	1,096
Proceeds from bank owned life insurance	772	178
Other, net	(713)	1,280	(196)
Net cash provided by (used in) investing activities	16,314	5,220	4,406
Cash flows from financing activities:
Net change in purchased funds and other short-term borrowings			(40)
Repayment of long-term debt	(375)	(1,500)	(1,500)
Payment for repurchase of trust preferred securities	(20,619)
Purchases of treasury stock	(12,012)	(2,319)	(1,928)
Stock issued under dividend reinvestment and employee stock purchase plans	2,422	2,515	2,287
Cash dividends paid	(10,029)	(16,755)	(13,367)
Net cash (used in) provided by financing activities	(40,613)	(18,059)	(14,548)
Net (decrease) increase in cash and due from financial institutions	(9,557)	10,002	1,906
Cash and due from banks at beginning of year	12,556	2,554	648
Cash and due from banks at end of year	2,999	12,556	2,554
Cash paid during the year for:
Interest	754	1,194	1,211
Income tax, net of refunds received	$ 5,017	$ 1,180	$ 4,445