Consolidated Statements of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
OPERATING ACTIVITIES
Net income	$ 75,610,000	$ 71,947,000	$ 67,298,000
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	17,141,000	13,773,000	46,065,000
Depreciation, amortization and accretion	7,340,000	6,788,000	6,823,000
Loss on sales of bank premises, OREO and equipment	1,072,000	1,835,000	1,594,000
Loss on securities transactions	18,838,000	7,809,000	14,705,000
Loans originated for sale	(66,990,000)	(49,181,000)	(74,089,000)
Proceeds from sales of loans	72,971,000	48,258,000	70,281,000
Gain on sales of loans	(952,000)	(662,000)	(608,000)
Stock-based compensation	1,133,000	1,050,000	484,000
Deferred income tax expense (benefit)	10,907,000	6,582,000	(6,625,000)
Contribution to pension plan	0	(9,100,000)	(11,000,000)
Amortization of net periodic pension costs	912,000	1,467,000	4,470,000
Changes in:
Interest receivable	(2,897,000)	3,594,000	4,658,000
Other assets	(1,866,000)	(39,000)	(63,037,000)
Accrued expenses and other liabilities	(14,652,000)	(3,297,000)	(7,362,000)
NET CASH PROVIDED BY OPERATING ACTIVITIES	118,567,000	100,824,000	53,657,000
INVESTING ACTIVITIES
Proceeds from maturities and calls of held to maturity securities	7,635,000	6,480,000	31,353,000
Proceeds from sales of securities held to maturity	0	2,979,000	0
Proceeds from sales of securities available for sale	24,763,000	57,294,000	5,500,000
Proceeds from maturities and calls of securities available for sale	1,462,173,000	1,331,904,000	507,287,000
Purchases of securities available for sale	(1,417,978,000)	(1,236,221,000)	(233,160,000)
Redemption of bank-owned life insurance policies	822,000	0	0
Purchases of bank premises and equipment	(7,994,000)	(3,262,000)	(4,947,000)
Acquisition of Centra Financial Holdings, Inc., net of cash acquired	49,085,000	0	0
Proceeds from sales and redemptions of other investment securities	10,819,000	4,816,000	21,000
Purchases of other investment securities	(338,000)	(173,000)	(204,000)
Net change in loans	29,350,000	468,106,000	239,311,000
NET CASH PROVIDED BY INVESTING ACTIVITIES	158,337,000	631,923,000	545,161,000
FINANCING ACTIVITIES
Cash dividends paid	(54,344,000)	(52,257,000)	(50,383,000)
Excess tax benefits from stock-based compensation arrangements	3,114,000	459,000	273,000
Acquisition of treasury stock	(18,000)	(11,000)	(1,180,000)
Proceeds from exercise of stock options	542,000	2,492,000	724,000
Proceeds from sales of treasury stock from deferred compensation plan	74,000	520,000	536,000
Repayment of long-term Federal Home Loan Bank borrowings	(60,372,000)	(385,032,000)	(80,325,000)
Changes in:
Time deposits	(274,652,000)	(591,732,000)	(162,714,000)
Other deposits	250,380,000	334,166,000	485,860,000
Federal funds purchased, securities sold under agreements to repurchase and other short-term borrowings	32,986,000	(29,730,000)	(555,376,000)
NET CASH USED IN FINANCING ACTIVITIES	(102,290,000)	(721,125,000)	(362,585,000)
INCREASE IN CASH AND CASH EQUIVALENTS	174,614,000	11,622,000	236,233,000
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	461,389,000	449,767,000	213,534,000
CASH AND CASH EQUIVALENTS AT END OF YEAR	$ 636,003,000	$ 461,389,000	$ 449,767,000