Note 4 - Loans and Allowance for Credit Losses (Detail) - Loans by delinquency and nonaccrual status (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Current and Accruing	$ 1,983,655		$ 2,050,959
30-89 Days Past Due and Accruing	23,738		27,489
Past Due 90 days or More and Accruing	393		614
Nonaccrual	29,148		32,295
Total Loans	2,036,934		2,111,357
Originated Loans [Member] | Commercial Portfolio Segment [Member]
Current and Accruing	313,381		333,474
30-89 Days Past Due and Accruing	2,493		1,032
Nonaccrual	2,628		5,610
Total Loans	318,502		340,116
Originated Loans [Member] | Commercial Real Estate Portfolio Segment [Member]
Current and Accruing	613,517		616,276
30-89 Days Past Due and Accruing	6,427		10,750
Nonaccrual	5,241		5,901
Total Loans	625,185		632,927
Originated Loans [Member] | Construction Portfolio Segment [Member]
Current and Accruing	7,920		7,984
Total Loans	7,920		7,984
Originated Loans [Member] | Residential Portfolio Segment [Member]
Current and Accruing	213,353		220,032
30-89 Days Past Due and Accruing	333		2,193
Nonaccrual	233		233
Total Loans	213,919		222,458
Originated Loans [Member] | Consumer Portfolio Segment [Member]
Current and Accruing	444,284		455,007
30-89 Days Past Due and Accruing	3,224		5,205
Past Due 90 days or More and Accruing	305		455
Nonaccrual	57		31
Total Loans	447,870		460,698
Originated Loans [Member]
Current and Accruing	1,592,455		1,632,773
30-89 Days Past Due and Accruing	12,477		19,180
Past Due 90 days or More and Accruing	305		455
Nonaccrual	8,159		11,775
Total Loans	1,613,396		1,664,183
Purchased Non-Covered Loans [Member]
Current and Accruing	60,242		65,567
30-89 Days Past Due and Accruing	1,150		1,821
Past Due 90 days or More and Accruing			4
Nonaccrual	9,112		7,499
Total Loans	70,504		74,891
Purchased Covered Loans [Member]
Current and Accruing	330,958		352,619
30-89 Days Past Due and Accruing	10,111		6,488
Past Due 90 days or More and Accruing	88		155
Nonaccrual	11,877		13,021
Total Loans	353,034	[1]	372,283	[1]
Commercial Portfolio Segment [Member]
Total Loans	379,124		401,331
Commercial Real Estate Portfolio Segment [Member]
Total Loans	893,247		916,594
Construction Portfolio Segment [Member]
Total Loans	15,685		16,515
Residential Portfolio Segment [Member]
Total Loans	224,244		234,035
Consumer Portfolio Segment [Member]
Total Loans	$ 524,634		$ 542,882

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