Consolidated Statements Of Cash Flows (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
CASH FLOWS FROM OPERATING ACTIVITIES:
Net earnings	$ 50,902	$ 44,144
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	5,461	5,275
Provision for loan losses	5,405	6,971
Securities premium amortization (discount accretion), net	5,279	3,236
Gain on sale of assets, net	(26)	(2,570)
Deferred federal income tax expense	1,885	254
Change in loans held for sale	6,898	(4,624)
Change in other assets	1,467	3,930
Change in other liabilities	4,201	5,136
Total adjustments	30,570	17,608
Net cash provided by operating activities	81,472	61,752
CASH FLOWS FROM INVESTING ACTIVITIES:
Sales	13,244	17,403
Maturities	1,380,354	145,720
Purchases	(1,542,627)	(255,153)
Activity in held-to-maturity securities - maturities	4,703	6,049
Net increase in loans	(53,340)	(33,107)
Purchases of bank premises and equipment and computer software	(9,947)	(9,090)
Proceeds from sale of other assets	4,732	8,750
Net cash used in investing activities	(202,881)	(119,428)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase (decrease) in noninterest-bearing deposits	61,479	(55,095)
Net increase in interest-bearing deposits	11,825	108,984
Net increase in short-term borrowings	2,434	32,003
Common stock transactions:
Proceeds from stock issuances	821	658
Dividends paid	(21,811)	(21,256)
Net cash provided by financing activities	54,748	65,294
NET DECREASE (INCREASE) IN CASH AND CASH EQUIVALENTS	(66,661)	7,618
CASH AND CASH EQUIVALENTS, beginning of period	367,953	321,541
CASH AND CASH EQUIVALENTS, end of period	301,292	329,159
SUPPLEMENTAL INFORMATION AND NONCASH TRANSACTIONS
Interest paid	6,962	10,830
Federal income tax paid	13,824	12,994
Transfer of loans to foreclosed assets	5,747	9,822
Investment securities purchased but not settled	$ 19,797	$ 35,830