Note 4 - Debt and Equity Securities (Details) - Amortized Cost and Fair Value of Securities Available-for-sale (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Note 4 - Debt and Equity Securities (Details) - Amortized Cost and Fair Value of Securities Available-for-sale [Line Items]
Amortized Cost	$ 994,079	$ 967,329
Fair Value	1,007,684us-gaap_AvailableForSaleSecurities	973,310us-gaap_AvailableForSaleSecurities
Gross Unrealized Gains	17,513	13,240
Gross Unrealized Losses	3,908	7,259
Corporate Debt Securities [Member]
Note 4 - Debt and Equity Securities (Details) - Amortized Cost and Fair Value of Securities Available-for-sale [Line Items]
Amortized Cost	95,785	90,719
Fair Value	95,750	91,273
Gross Unrealized Gains	939	1,268
Gross Unrealized Losses	974	714
Municipal [Member]
Note 4 - Debt and Equity Securities (Details) - Amortized Cost and Fair Value of Securities Available-for-sale [Line Items]
Amortized Cost	144,152	145,864
Fair Value	148,377	148,896
Gross Unrealized Gains	4,258	3,093
Gross Unrealized Losses	33	61
Mutual Funds [Member]
Note 4 - Debt and Equity Securities (Details) - Amortized Cost and Fair Value of Securities Available-for-sale [Line Items]
Amortized Cost	21,278	21,118
Fair Value	21,278	21,118
Other Debt Obligations [Member]
Note 4 - Debt and Equity Securities (Details) - Amortized Cost and Fair Value of Securities Available-for-sale [Line Items]
Amortized Cost	24,550	7,098
Fair Value	24,550	7,090
Gross Unrealized Gains	2
Gross Unrealized Losses	2	8
Available For Sale Securities, Excluding Mortgage-Backed Securities [Member]
Note 4 - Debt and Equity Securities (Details) - Amortized Cost and Fair Value of Securities Available-for-sale [Line Items]
Amortized Cost	285,765	264,799
Fair Value	289,955	268,377
Gross Unrealized Gains	5,199	4,361
Gross Unrealized Losses	1,009	783
REMIC And CMO [Member]
Note 4 - Debt and Equity Securities (Details) - Amortized Cost and Fair Value of Securities Available-for-sale [Line Items]
Amortized Cost	514,592	504,207
Fair Value	521,312	505,768
Gross Unrealized Gains	8,857	6,188
Gross Unrealized Losses	2,137	4,627
GNMA [Member]
Note 4 - Debt and Equity Securities (Details) - Amortized Cost and Fair Value of Securities Available-for-sale [Line Items]
Amortized Cost	13,359	13,862
Fair Value	13,733	14,159
Gross Unrealized Gains	455	421
Gross Unrealized Losses	81	124
FNMA [Member]
Note 4 - Debt and Equity Securities (Details) - Amortized Cost and Fair Value of Securities Available-for-sale [Line Items]
Amortized Cost	166,451	169,956
Fair Value	168,556	170,367
Gross Unrealized Gains	2,786	2,128
Gross Unrealized Losses	681	1,717
FHLMC [Member]
Note 4 - Debt and Equity Securities (Details) - Amortized Cost and Fair Value of Securities Available-for-sale [Line Items]
Amortized Cost	13,912	14,505
Fair Value	14,128	14,639
Gross Unrealized Gains	216	142
Gross Unrealized Losses		8
Collateralized Mortgage Obligations [Member]
Note 4 - Debt and Equity Securities (Details) - Amortized Cost and Fair Value of Securities Available-for-sale [Line Items]
Amortized Cost	708,314	702,530
Fair Value	717,729	704,933
Gross Unrealized Gains	12,314	8,879
Gross Unrealized Losses	$ 2,899	$ 6,476

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount of unrealized gain before deducting unrealized loss on investments in debt and equity securities classified as available-for-sale securities.

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Amount of unrealized loss before deducting unrealized gain on investments in available-for-sale securities.

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