Note 4 - Loans (Detail) - Loan Portfolio (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Commercial and industrial	$ 1,631,474		$ 1,458,446
Agricultural	268,618		243,776
Commercial real estate:
Office, retail, and industrial	1,333,191		1,299,082
Multi-family	285,481		288,336
Residential construction	61,462		105,836
Commercial construction	124,954		144,909
Other commercial real estate	773,121		888,146
Total commercial real estate	2,578,209		2,726,309
Total corporate loans	4,478,301		4,428,531
Home equity	390,033		416,194
1-4 family mortgages	282,948		201,099
Installment loans	38,394		42,289
Total consumer loans	711,375		659,582
Total loans, excluding covered loans	5,189,676		5,088,113
Covered loans (1)	197,894	[1]	260,502
Total loans	5,387,570		5,348,615
Deferred loan fees included in total loans	5,941		7,828
Overdrawn demand deposits included in total loans	$ 4,451		$ 2,850

[1] For information on covered loans, refer to Note 5, "Covered Assets."