Note 15 - Regulatory Capital (Details) - Summary of the Bank’s Compliance with Banking Regulatory Capital Standards - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Savings Bank [Member]
Tier I (leverage) capital:
Capital level	$ 488,327	$ 472,251
Capital level	9.02%	9.63%
Requirement to be well capitalized	$ 270,676	$ 245,254
Requirement to be well capitalized	5.00%	5.00%
Excess	$ 217,651	$ 226,997
Excess	4.02%	4.63%
Common Equity Tier I risk-based capital:
Capital level	$ 488,327	$ 0
Capital level	12.86%	0.00%
Requirement to be well capitalized	$ 246,781	$ 0
Requirement to be well capitalized	6.50%	0.00%
Excess	$ 241,546	$ 0
Excess	6.36%	0.00%
Tier 1 risk-based capital:
Capital level	$ 488,327	$ 472,251
Capital level	12.86%	13.87%
Requirement to be well capitalized	$ 303,731	$ 204,345
Requirement to be well capitalized	8.00%	6.00%
Excess	$ 184,596	$ 267,906
Excess	4.86%	7.87%
Total risk-based capital:
Capital level	$ 511,300	$ 497,347
Capital level	13.47%	14.60%
Requirement to be well capitalized	$ 379,664	$ 340,589
Requirement to be well capitalized	10.00%	10.00%
Excess	$ 131,636	$ 156,758
Excess	3.47%	4.60%
Holding Company [Member]
Tier I (leverage) capital:
Capital level	$ 482,684	$ 471,233
Capital level	8.93%	9.62%
Requirement to be well capitalized	$ 270,288	$ 244,960
Requirement to be well capitalized	5.00%	5.00%
Excess	$ 212,396	$ 226,273
Excess	3.93%	4.62%
Common Equity Tier I risk-based capital:
Capital level	$ 455,153	$ 0
Capital level	12.01%	0.00%
Requirement to be well capitalized	$ 246,358	$ 0
Requirement to be well capitalized	6.50%	0.00%
Excess	$ 208,795	$ 0
Excess	5.51%	0.00%
Tier 1 risk-based capital:
Capital level	$ 482,684	$ 471,233
Capital level	12.74%	13.87%
Requirement to be well capitalized	$ 303,209	$ 203,878
Requirement to be well capitalized	8.00%	6.00%
Excess	$ 179,475	$ 267,355
Excess	4.74%	7.87%
Total risk-based capital:
Capital level	$ 505,657	$ 496,329
Capital level	13.34%	14.61%
Requirement to be well capitalized	$ 379,012	$ 339,797
Requirement to be well capitalized	10.00%	10.00%
Excess	$ 126,645	$ 156,532
Excess	3.34%	4.61%

Common Equity Tier I risk-based capital as defined in the regulations.

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The amount by which the company's Common Equity Tier I risk-based capital exceeds the minimum required for capital adequacy purposes.

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Common Equity Tier I risk-based capital excess ratio as defined by regulations.

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Common Equity Tier I risk-based capital ratio as defined by regulations.

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The amount of Common Equity Tier I risk-based capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.

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Common Equity Tier I risk-based capital ratio to be well capitalized as defined by regulations.

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The amount of total capital as defined in the regulations.

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The amount of Total Capital required to be categorized as well as capitalized under the regulatory framework for prompt corrective action.

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The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action.

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Total Capital divided by risk weighted assets as defined in the regulations.

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The amount by which the company's Total Capital exceeds the minimum required for capital adequacy purposes.

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The amount of excess Total Capital divided by risk weighted assets which are assets that are weighted for credit risk according to a formula used by the Reserve Bank.

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The amount by which the company's Tier 1 Leverage Capital exceeds the minimum required for capital adequacy purposes.

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The amount of excess Tier 1 Leverage Capital divided by average assets as defined in the regulations.

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The amount by which the company's Tier 1 Risk Based Capital exceeds the minimum required for capital adequacy purposes.

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The amount of excess Tier 1 Risk Based Capital (which consists of the types of financial capital considered the most reliable and liquid, primarily Shareholders' equity. Examples of Tier 1 capital are common stock or unit, preferred stock or unit that is irredeemable and noncumulative, and retained earnings) divided by risk-weighted assets which are assets that are weighted for credit risk according to a formula used by the Reserve Bank.

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Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

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The amount of Tier 1 Leverage Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.

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The amount of Tier 1 Leverage Capital required to be categorized as well capitalized divided by average assets as defined in the regulatory framework for prompt corrective action.

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Tier 1 Leverage Capital divided by average assets as defined in the regulations.

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Tier 1 Risk Based Capital as defined in the regulations.

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The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action.

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Tier 1 capital divided by risk weighted assets as defined by regulations.

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