Note 12 - Pension and Other Postretirement Benefit Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 1995
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets
Equity Securities [Member] | Minimum [Member] | Retirement Plan [Member] | Savings Bank [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	8.00%
Equity Securities [Member] | Maximum [Member] | Retirement Plan [Member] | Savings Bank [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	10.00%
Equity Securities [Member] | Retirement Plan [Member] | Savings Bank [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	60.00%
Fixed Income Securities [Member] | Minimum [Member] | Retirement Plan [Member] | Savings Bank [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	3.00%
Fixed Income Securities [Member] | Maximum [Member] | Retirement Plan [Member] | Savings Bank [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	5.00%
Fixed Income Securities [Member] | Retirement Plan [Member] | Savings Bank [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	40.00%
Trust for Benefit of Employees [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Full Time Employment Years of Service	1 year
Amount Borrowed From the Company by the Employee Benefit Trust (in Dollars)				$ 7,900,000
Stock Issued During Period, Value, Employee Benefit Plan (in Dollars)				7,000
Stock Issued During Period, Shares, Employee Benefit Plan (in Shares)				2,328,750
Employer Contributions to the 401(k) and Profit Sharing Plans Funded By the Employee Benefit Trust (in Dollars)	2,700,000	2,300,000	2,100,000
U.S. large-cap growth [Member] | Minimum [Member] | Retirement Plan [Member] | Savings Bank [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Number of Stocks Held in Portfolio	55
U.S. large-cap growth [Member] | Maximum [Member] | Retirement Plan [Member] | Savings Bank [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Number of Stocks Held in Portfolio	70
U.S. Small-Cap Blend [Member] | Minimum [Member] | Retirement Plan [Member] | Savings Bank [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Number of Stocks Held in Portfolio	40
U.S. Small-Cap Blend [Member] | Maximum [Member] | Retirement Plan [Member] | Savings Bank [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Number of Stocks Held in Portfolio	100
U.S. Small-Cap Blend [Member] | Retirement Plan [Member] | Savings Bank [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Pension Plan Assets, Equity Securities Held in Mutual Funds, Minimum Market Capitalization (in Dollars)	100,000,000
International blend [Member] | Minimum [Member] | Retirement Plan [Member] | Savings Bank [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Number of Stocks Held in Portfolio	80
International blend [Member] | Maximum [Member] | Retirement Plan [Member] | Savings Bank [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Number of Stocks Held in Portfolio	90
In Event of Termination [Member] | Less Than [Member] | Directors' Plan [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Full Time Employment Years of Service	2 years
In Event of Termination [Member] | Directors' Plan [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Full Time Employment Years of Service	2 years
Defined Benefit Contributions, Months of Benefit Used In Lump Sum Payment	120 months
Minimum [Member] | Retirement Plan [Member] | Savings Bank [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	8.00%
Minimum [Member] | Retirement Plan [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Benefit Plan, Benefit Service Period	3 years
Maximum [Member] | Retirement Plan [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Benefit Plan, Benefit Service Period	10 years
Retirement Plan [Member] | Savings Bank [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Benefit Plan, Contributions by Employer (in Dollars)		800,000	700,000
Defined Benefit Plan, Benefit Obligation (in Dollars)	24,100,000	19,700,000
Retirement Plan [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Benefit Plan, Contributions by Employer (in Dollars)		831,000
Defined Benefit Plan, Benefit Obligation (in Dollars)	24,097,000	19,740,000	22,531,000
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	7.50%	7.50%	7.50%
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months (in Dollars)	1,094,000
Postretirement Plans [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Benefit Plan, Contributions by Employer (in Dollars)	49,000	66,000
Defined Benefit Plan, Benefit Obligation (in Dollars)	8,073,000	5,586,000	5,927,000
Number of Unfunded Postretirement Benefit Plans	2
Full Time Employment Years of Service	5 years
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months (in Dollars)	181,000
Postretirement Plan 1 [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Cost Sharing Arrangement, Medical Benefits, Percentage	50.00%
Medical Premiums, Required Percentage to Be Paid By Spouses of Future Retirees	100.00%
401(k) [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Contribution Plan Service Period Requirement	1 year
Directors' Plan [Member] | Savings Bank [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Benefit Plan, Benefit Obligation (in Dollars)	2,700,000	2,700,000
Annual Retirement Benefit Paid to Terminating Eligible Directors (in Dollars)	48,000
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year (in Dollars)	288,000
Directors' Plan [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Benefit Plan, Contributions by Employer (in Dollars)	120,000	98,000
Defined Benefit Plan, Benefit Obligation (in Dollars)	2,663,000	2,666,000	2,706,000
Full Time Employment Years of Service	5 years
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months (in Dollars)	288,000
401(k) [Member] | Savings Bank [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Contribution Plan Annual Employer Matching Of Employee's Contribution Percent	50.00%
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	3.00%
401(k) [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Contribution Plan, Employers Matching Contribution, Annual Vesting Percentage	20.00%
Defined Contribution Plan, Vesting Period	5 years
Defined Contribution Plan, Employers Matching Contribution, Vesting Percentage Upon Change of Control	100.00%
Defined Contribution Plan, Cost Recognized (in Dollars)	3,100,000	2,900,000	2,400,000
Defined Contribution Retirement Plan ("DCRP") [Member] | Savings Bank [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	4.00%
Non-Qualified Deferred Compensation Plan [Member]
Note 12 - Pension and Other Postretirement Benefit Plans (Details) [Line Items]
Defined Contribution Plan Annual Employer Matching Of Employee's Contribution Percent	50.00%
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	5.00%
Defined Contribution Plan, Employers Matching Contribution, Annual Vesting Percentage	20.00%
Defined Contribution Plan, Vesting Period	5 years
Defined Contribution Plan, Employers Matching Contribution, Vesting Percentage Upon Change of Control	100.00%
Defined Contribution Plan, Cost Recognized (in Dollars)	$ 400,000	$ 400,000	$ 400,000