Note 7 - Investment Securities (Details) - Pooled Trust Preferred Securities		9 Months Ended
		Sep. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
Note 7 - Investment Securities (Details) - Pooled Trust Preferred Securities [Line Items]
Book value		$ 360,660,000	$ 373,844,000
Investment securities available-for-sale		$ 362,568,000	375,219,000
PreTSL IV [Member]
Note 7 - Investment Securities (Details) - Pooled Trust Preferred Securities [Line Items]
Class	[1]	Mezzanine*
Book value	[1]	$ 243,000
Investment securities available-for-sale	[1]	217,000
Unrealized gains (losses)	[1]	$ (26,000)
Realized OTTI credit loss	[1]
Total recognized OTTI credit loss	[1]	$ (1,000)
Moody's/Fitch ratings	[1]	B1/BB
Current number of performing banks	[1]	5
Current number of performing insurance companies	[1]
Actual deferrals and defaults as a % of total collateral	[1]	18.00%
Total performing collateral as a % of outstanding bonds	[1]	140.70%
PreTSL XVII [Member]
Note 7 - Investment Securities (Details) - Pooled Trust Preferred Securities [Line Items]
Class		Mezzanine
Book value		$ 705,000
Investment securities available-for-sale		523,000
Unrealized gains (losses)		(182,000)
Total recognized OTTI credit loss		$ (222,000)
Moody's/Fitch ratings		C/CC
Current number of performing banks		33
Current number of performing insurance companies		5
Actual deferrals and defaults as a % of total collateral		26.70%
Total performing collateral as a % of outstanding bonds		91.20%
PreTSL XIX [Member]
Note 7 - Investment Securities (Details) - Pooled Trust Preferred Securities [Line Items]
Class		Mezzanine
Book value		$ 987,000
Investment securities available-for-sale		554,000
Unrealized gains (losses)		(433,000)
Total recognized OTTI credit loss		$ 0
Moody's/Fitch ratings		Caa3/CC
Current number of performing banks		40
Current number of performing insurance companies		12
Actual deferrals and defaults as a % of total collateral		12.20%
Total performing collateral as a % of outstanding bonds		94.80%
PreTSL XXV [Member]
Note 7 - Investment Securities (Details) - Pooled Trust Preferred Securities [Line Items]
Class		Mezzanine
Book value		$ 766,000
Investment securities available-for-sale		480,000
Unrealized gains (losses)		(286,000)
Total recognized OTTI credit loss		$ (222,000)
Moody's/Fitch ratings		C/C
Current number of performing banks		46
Current number of performing insurance companies		5
Actual deferrals and defaults as a % of total collateral		28.30%
Total performing collateral as a % of outstanding bonds		88.80%
Collateralized Debt Obligations [Member]
Note 7 - Investment Securities (Details) - Pooled Trust Preferred Securities [Line Items]
Book value		$ 3,409,000	3,519,000
Investment securities available-for-sale		2,600,000	$ 2,439,000
Unrealized gains (losses)		(809,000)
Total recognized OTTI credit loss		$ (1,153,000)
Security 1 [Member] | PreTSL XXVI [Member]
Note 7 - Investment Securities (Details) - Pooled Trust Preferred Securities [Line Items]
Class		Mezzanine
Book value		$ 454,000
Investment securities available-for-sale		357,000
Unrealized gains (losses)		(97,000)
Total recognized OTTI credit loss		$ (270,000)
Moody's/Fitch ratings		Caa3/C
Current number of performing banks		42
Current number of performing insurance companies		7
Actual deferrals and defaults as a % of total collateral		21.00%
Total performing collateral as a % of outstanding bonds		94.40%
Security 2 [Member] | PreTSL XXVI [Member]
Note 7 - Investment Securities (Details) - Pooled Trust Preferred Securities [Line Items]
Class		Mezzanine
Book value		$ 254,000
Investment securities available-for-sale		469,000
Unrealized gains (losses)		215,000
Total recognized OTTI credit loss		$ (438,000)
Moody's/Fitch ratings		Caa3/C
Current number of performing banks		42
Current number of performing insurance companies		7
Actual deferrals and defaults as a % of total collateral		21.00%
Total performing collateral as a % of outstanding bonds		94.40%

[1] only class of bonds still outstanding (represents the senior-most obligation of the trust)