Consolidated Statements of Cash Flows (USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 15,021,000	$ 14,261,000
Adjustments to reconcile net income to net cash provided by operating activities:
Mortgage loans originated for sale	(60,165,000)	(10,812,000)
Proceeds from mortgage loans sold	64,219,000	14,497,000
Gain on sales of mortgage loans held for sale	(1,238,000)	(296,000)
Net gain on sales of investments	(2,665,000)	(1,119,000)
Provision for loan losses	2,250,000	3,250,000
Deferred income taxes	(1,297,000)	(1,377,000)
Net depreciation and amortization	4,421,000	4,838,000
(Decrease) increase in accrued interest receivable	(265,000)	156,000
Gain on sale of other real estate owned		(4,000)
Increase in other assets	(4,321,000)	(3,303,000)
Increase in other liabilities	3,527,000	3,788,000
Net cash provided by operating activities	19,487,000	23,879,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from maturities of short-term investments	16,317,000	23,351,000
Purchase of short-term investments	(8,561,000)	(36,364,000)
Proceeds from calls/maturities of securities available-for-sale	228,212,000	429,440,000
Proceeds from sales of securities available-for-sale	216,078,000	271,500,000
Purchase of securities available-for-sale	(536,612,000)	(654,900,000)
Proceeds from calls/maturities of securities held-to-maturity	79,249,000	69,831,000
Purchase of securities held-to-maturity	(190,718,000)	(175,343,000)
Net increase in loans	(122,241,000)	(85,354,000)
Proceeds from sales of other real estate owned		1,187,000
Capital expenditures	(1,232,000)	(3,309,000)
Net cash used in investing activities	(319,508,000)	(159,961,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net decrease in time deposits	(68,433,000)	(1,871,000)
Net increase in demand, savings, money market and NOW deposits	311,489,000	220,570,000
Net proceeds from exercise of stock options	43,000	137,000
Cash dividends	(1,642,000)	(1,639,000)
Net (decrease) increase in securities sold under agreements to repurchase	(6,230,000)	32,740,000
Net increase (decrease) in other borrowed funds	46,000,000	(59,999,000)
Net cash provided by financing activities	281,227,000	189,938,000
Net (decrease) increase in cash and cash equivalents	(18,794,000)	53,856,000
Cash and cash equivalents at beginning of period	152,283,000	207,766,000
Cash and cash equivalents at end of period	133,489,000	261,622,000
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid during the period for interest	13,993,000	14,828,000
Cash paid during the period for income taxes	2,898,000	1,828,000
Change in unrealized (losses) gains on securities available-for-sale, net of taxes	(12,969,000)	4,217,000
Change in unrealized losses on securities transferred to held-to-maturity, net of taxes	(14,643,000)
Pension liability adjustment, net of taxes	520,000	487,000
Due to broker	3,086,000	10,750,000
Transfer of loans to other real estate owned		400,000
Transfer of securities available-for-sale to held-to-maturity	$ 987,037,000