Note 4 - Loans (Details) - Loan Portfolio (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Loan Portfolio [Abstract]
Commercial and industrial	$ 1,743,139		$ 1,631,474
Agricultural	288,632		268,618
Office, retail, and industrial	1,319,849		1,333,191
Multi-family	306,182		285,481
Residential construction	50,384		61,462
Commercial construction	117,116		124,954
Other commercial real estate	759,367		773,121
Total commercial real estate	2,552,898		2,578,209
Total corporate loans	4,584,669		4,478,301
Home equity	374,406		390,033
1-4 family mortgages	291,770		282,948
Installment	36,720		38,394
Total consumer loans	702,896		711,375
Total loans, excluding covered loans	5,287,565		5,189,676
Covered loans (1)	171,861	[1]	197,894	[1]
Total loans	5,459,426		5,387,570
Deferred loan fees included in total loans	5,180		5,941
Overdrawn demand deposits included in total loans	$ 3,001		$ 4,451

[1] For information on covered loans, refer to Note 5, "Acquired Loans."