Percentage of the cost sharing arrangement relating to medical benefits under a postretirement plan.

No definition available.

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- Definition

The amount held in a rabbi trust for certain non-qualified deferred compensation plans.

+ References

No definition available.

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- Definition

The period of time the benefits used in a lump sum payment in the event of a termination with the defined benefits contribution.

+ References

No definition available.

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- Definition

The amount of annual retirement benefit in a defined benefit plan.

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No definition available.

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- Definition

Represents defined Benefit plan benefit services period.

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No definition available.

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- Definition

Percentage of employees' annual contributions for which the employer contributes a matching contribution to a defined contribution plan, up to a specified limit.

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No definition available.

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- Definition

Percentage of employer's matching contributions to a defined contribution plan that vests due to a change of control (as defined in the applicable plan).

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No definition available.

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- Definition

Service period required to participate in the Defined Contribution Plan.

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Represents the vesting period of a defined contribution plan.

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No definition available.

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- Definition

Employer contributions to the 401(k) and profit sharing plans funded by the Employee Benefit Trust.

+ References

No definition available.

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- Definition

Represents full time employment years of service.

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No definition available.

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- Definition

Required percentage of medical premiums to be paid by spouses of future retirees.

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No definition available.

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- Definition

Represents the number of unfunded postretirement benefit plans.

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No definition available.

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- Definition

Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan.

+ References

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- Definition

Amount of contribution received by defined benefit plan from employer which increases plan assets.

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- Definition

Amount of benefits for defined benefit plan expected to be paid in next fiscal year following latest fiscal year.

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- Definition

Amount of contributions expected to be received by defined benefit plan from employer in next fiscal year following latest fiscal year.

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- Definition

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

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Amount of cost for defined contribution plan.

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- Definition

Percentage of employer's matching contributions to a defined contribution plan that vests in a given year.

+ References

No definition available.

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- Definition

Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan.

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No definition available.

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Pension and Other Postretirement Benefit Plans (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) plan	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Trust for Benefit of Employees [Member]
Full Time Employment, Years of Service	1 year
Employer Contributions to the 401(k) and Profit Sharing Plans Funded By the Employee Benefit Trust	$ 3,400,000	$ 3,600,000	$ 3,200,000
Retirement Plan [Member]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	5.25%	7.00%	7.00%
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	$ 1,317,000
Retirement Plan [Member] \| Savings Bank [Member]
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 0	$ 0	$ 0
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	5.25%
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 0
Retirement Plan [Member] \| Savings Bank [Member] \| Defined Benefit Plan, Equity Securities [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	60.00%
Retirement Plan [Member] \| Savings Bank [Member] \| Fixed Income Securities [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	40.00%
Retirement Plan [Member] \| Minimum [Member]
Defined Benefit Plan, Benefit Service Period	3 years
Retirement Plan [Member] \| Minimum [Member] \| Savings Bank [Member] \| Defined Benefit Plan, Equity Securities [Member]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	8.00%
Retirement Plan [Member] \| Minimum [Member] \| Savings Bank [Member] \| Fixed Income Securities [Member]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	3.00%
Retirement Plan [Member] \| Maximum [Member]
Defined Benefit Plan, Benefit Service Period	10 years
Retirement Plan [Member] \| Maximum [Member] \| Savings Bank [Member] \| Defined Benefit Plan, Equity Securities [Member]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	10.00%
Retirement Plan [Member] \| Maximum [Member] \| Savings Bank [Member] \| Fixed Income Securities [Member]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	5.00%
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 76,000	88,000
Number of Unfunded Postretirement Benefit Plans \| plan	2
Full Time Employment, Years of Service	5 years
Cost Sharing Arrangement, Medical Benefits Percentage	50.00%
Medical Premiums, Required Percentage to Be Paid By Spouses of Future Retirees	100.00%
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	$ 252,000
The 401(k) Plan [Member]
Defined Contribution Plan, Employers Matching Contribution, Annual Vesting Percentage	20.00%
Defined Contribution Plan, Employer's Matching Contribution, Vesting Percentage, Upon Change of Control	100.00%
Defined Contribution Plan, Cost	$ 3,000,000.0	4,100,000	3,400,000
The 401(k) Plan [Member] \| Savings Bank [Member]
Defined Contribution Plan, Annual Employer Matching of Employees Contribution, Percent	50.00%
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	3.00%
Defined Contribution Retirement Plan ("DCRP") [Member] \| Savings Bank [Member]
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	4.00%
Non-qualified Deferred Compensation Plan [Member]
Defined Contribution Plan, Annual Employer Matching of Employees 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, Employer's Matching Contribution, Vesting Percentage, Upon Change of Control	100.00%
Defined Contribution Plan, Cost	$ 500,000	500,000	$ 400,000
Defined Contribution Plan, Service Period Requirement	1 year
Defined Contribution Plan, Vesting Period	5 years
Deferred Compensation Plan, Amounts Held in Rabbi Trust	$ 14,400,000	11,400,000
Directors' Plan [Member]
Defined Benefit Plan, Plan Assets, Contributions by Employer	144,000	96,000
Deferred Compensation Plan, Amounts Held in Rabbi Trust	4,300,000	$ 4,800,000
Defined Benefit Plan, Annual Retirement Benefit	$ 48,000
Defined Benefit Contributions, Months of Benefit Used in Lump Sum Payment in the Event of Termination	10 years
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	$ 288,000