Note 4 - Loans and Allowance for Credit Losses (Detail) - Credit risk profile by internally assigned grade (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Grade:
Loans by grade	$ 2,036,934		$ 2,111,357
Pass [Member] | Commercial [Member]
Grade:
Loans by grade	305,285		324,452
Pass [Member] | Commercial Real Estate Loans [Member]
Grade:
Loans by grade	590,834		599,472
Pass [Member] | Construction [Member]
Grade:
Loans by grade	7,457		7,518
Pass [Member] | Residential Real Estate Loans [Member]
Grade:
Loans by grade	211,445		219,655
Pass [Member] | Consumer Installment And Other [Member]
Grade:
Loans by grade	446,365		459,076
Pass [Member] | Purchased Non-Covered Loans [Member]
Grade:
Loans by grade	48,379		51,901
Pass [Member] | Purchased Covered Loans [Member]
Grade:
Loans by grade	253,854	[1]	274,976	[1]
Pass [Member]
Grade:
Loans by grade	1,863,619		1,937,050
Substandard [Member] | Commercial [Member]
Grade:
Loans by grade	10,798		11,413
Substandard [Member] | Commercial Real Estate Loans [Member]
Grade:
Loans by grade	34,351		33,455
Substandard [Member] | Construction [Member]
Grade:
Loans by grade	463		466
Substandard [Member] | Residential Real Estate Loans [Member]
Grade:
Loans by grade	2,474		2,803
Substandard [Member] | Consumer Installment And Other [Member]
Grade:
Loans by grade	1,224		1,158
Substandard [Member] | Purchased Non-Covered Loans [Member]
Grade:
Loans by grade	25,172		27,066
Substandard [Member] | Purchased Covered Loans [Member]
Grade:
Loans by grade	121,300	[1]	122,815	[1]
Substandard [Member]
Grade:
Loans by grade	195,782		199,176
Doubtful [Member] | Commercial [Member]
Grade:
Loans by grade	2,419		4,251
Doubtful [Member] | Consumer Installment And Other [Member]
Grade:
Loans by grade	31		46
Doubtful [Member] | Purchased Non-Covered Loans [Member]
Grade:
Loans by grade	1,539		1,145
Doubtful [Member] | Purchased Covered Loans [Member]
Grade:
Loans by grade	455	[1]	470	[1]
Doubtful [Member]
Grade:
Loans by grade	4,444		5,912
Unlikely to be Collected Financing Receivable [Member] | Consumer Installment And Other [Member]
Grade:
Loans by grade	250		418
Unlikely to be Collected Financing Receivable [Member] | Purchased Non-Covered Loans [Member]
Grade:
Loans by grade			5
Unlikely to be Collected Financing Receivable [Member] | Purchased Covered Loans [Member]
Grade:
Loans by grade	85	[1]	150	[1]
Unlikely to be Collected Financing Receivable [Member]
Grade:
Loans by grade	335		573
Default Risk Purchase Discount [Member] | Purchased Non-Covered Loans [Member]
Grade:
Loans by grade	(4,586)		(5,226)
Default Risk Purchase Discount [Member] | Purchased Covered Loans [Member]
Grade:
Loans by grade	(22,660)	[1]	(26,128)	[1]
Default Risk Purchase Discount [Member]
Grade:
Loans by grade	(27,246)		(31,354)
Commercial [Member]
Grade:
Loans by grade	318,502		340,116
Commercial Real Estate Loans [Member]
Grade:
Loans by grade	625,185		632,927
Construction [Member]
Grade:
Loans by grade	7,920		7,984
Residential Real Estate Loans [Member]
Grade:
Loans by grade	213,919		222,458
Consumer Installment And Other [Member]
Grade:
Loans by grade	447,870		460,698
Purchased Non-Covered Loans [Member]
Grade:
Loans by grade	70,504		74,891
Purchased Covered Loans [Member]
Grade:
Loans by grade	$ 353,034	[1]	$ 372,283	[1]

[1] Credit risk profile reflects internally assigned grade of purchased covered loans without regard to FDIC indemnification.