Consolidated Statements of Financial Position (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Cash and cash equivalents:
Cash and cash due from banks	$ 123,519	$ 121,294	$ 126,712
Interest-bearing deposits with unaffiliated banks and others	315,201	260,646	484,572
Total cash and cash equivalents	438,720	381,940	611,284
Investment securities:
Available-for-sale at fair value	646,578	667,276	610,493
Held-to-maturity (fair value - $223,185 at September 30, 2012, $183,769 at December 31, 2011 and $185,024 at September 30, 2011)	221,536	183,339	186,432
Total investment securities	868,114	850,615	796,925
Loans held-for-sale	15,075	18,818	15,212
Loans	4,019,159	3,831,285	3,760,426
Allowance for loan losses	(84,694)	(88,333)	(88,713)
Net loans	3,934,465	3,742,952	3,671,713
Premises and equipment (net of accumulated depreciation of $91,203 at September 30, 2012, $86,991 at December 31, 2011 and $86,563 at September 30, 2011)	67,796	65,997	64,998
Goodwill	113,414	113,414	113,414
Other intangible assets	10,243	11,472	11,849
Interest receivable and other assets	132,594	154,245	154,209
Total Assets	5,580,421	5,339,453	5,439,604
Deposits:
Noninterest-bearing	952,126	875,791	891,363
Interest-bearing	3,646,746	3,491,066	3,589,223
Total deposits	4,598,872	4,366,857	4,480,586
Interest payable and other liabilities	34,738	54,024	33,700
Short-term Borrowings	311,471	303,786	302,298
Federal Home Loan Bank (FHLB) advances	37,237	43,057	45,991
Total liabilities	4,982,318	4,767,724	4,862,575
Shareholders' equity:
Preferred stock, no par value: Authorized - 200,000 shares, none issued	0	0	0
Common stock, $1 par value per share: Authorized - 45,000,000 shares; issued and outstanding - 27,498,094 at September 30, 2012, 27,456,907 at December 31, 2011 and 27,456,907 at September 30, 2011	27,498	27,457	27,457
Additional paid-in capital	432,627	431,277	430,462
Retained earnings	160,884	138,324	132,611
Accumulated other comprehensive loss	(22,906)	(25,329)	(13,501)
Total shareholders' equity	598,103	571,729	577,029
Total Liabilities and Shareholders' Equity	$ 5,580,421	$ 5,339,453	$ 5,439,604