v3.20.4

Note 13 - Retirement Plans - Funded Status of ACS Retirement Plan Using Beginning and Ending Balances for Projected Benefit Obligation and Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Interest cost	$ 476	$ 604
Fair value of plan assets at end of year	11,043
401K [Member]
Benefit obligation at beginning of year	15,158	14,499
Interest cost	476	604
Actuarial loss	1,442	1,221
Benefits paid	(1,051)	(1,166)
Benefit obligation at end of year	16,025	15,158
Fair value of plan assets at beginning of year	11,448	10,871
Actual return on plan assets	236	1,662
Employer contribution	858	81
Benefits paid	(1,051)	(1,166)
Fair value of plan assets at end of year	11,491	11,448
Funded status	$ (4,534)	$ (3,710)

Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

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Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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

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Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

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Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status.

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Amount of cost recognized for passage of time related to defined benefit plan.

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ALASKA COMMUNICATIONS SYSTEMS GROUP INC 10-K