CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash Flows From Operating Activities:
Net income	$ 23,303	$ 23,009	$ 20,310
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	6,916	4,528	4,026
Net gains on sales of securities	(2,635)	(43)	0
Stock-based compensation expense	1,399	1,390	1,472
Provisions for loan losses	2,400	2,150	4,100
Deferred income tax expense	974	2,145	1,268
Increase (decrease) in income tax liability	1,073	(192)	(487)
Decrease in pension liability	(2,158)	(6,817)	(4,259)
Other operating activities, net	4,056	(528)	(2,654)
Net cash provided by operating activities	35,328	25,642	23,776
Cash Flows From Investing Activities:
Proceeds from sales of securities available-for-sale	69,747	5,930	0
Proceeds from maturities of securities available-for-sale	11,898	18,510	4,770
Purchase of securities available-for-sale	(114,646)	(61,768)	(49,944)
Net (increase) decrease in loans	(19,165)	35,981	(67,169)
Increase in payments in excess of funding	(2,144)	(27,769)	(10,972)
Purchases of premises and equipment, net	(3,099)	(1,925)	(1,190)
Environmental management acquisition	(7,798)	0	0
Net cash used in investing activities	(65,207)	(31,041)	(124,505)
Cash Flows From Financing Activities:
Net increase (decrease) in noninterest-bearing demand deposits	12,187	18,859	(54)
Net increase in interest-bearing demand and savings deposits	21,683	36,956	39,392
Net (decrease) increase in time deposits	(18,530)	(26,037)	41,376
Net (decrease) increase in accounts and drafts payable	(72,440)	79,094	85,856
Cash dividends paid	(7,361)	(6,279)	(5,448)
Purchase of common shares of treasury	0	0	(467)
Other financing activities, net	(534)	(161)	(291)
Net cash (used in) provided by financing activities	(64,995)	102,432	160,364
Net (decrease) increase in cash and cash equivalents	(94,874)	97,033	59,635
Cash and cash equivalents at beginning of year	235,962	138,929	79,294
Cash and cash equivalents at end of year	141,088	235,962	138,929
Supplemental information:
Cash paid for interest	3,196	4,424	4,893
Cash paid for income taxes	$ 6,407	$ 6,287	$ 7,934