Pension Plan (Details) - Pension plan assets by level within the fair value hierarchy - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Pension plan assets, Total	$ 10,148,000	$ 8,647,000	$ 10,130,000
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Pension plan assets, Total	10,148,000	8,647,000
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Pension plan assets, Total
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Pension plan assets, Total
Equity And Index Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Pension plan assets, Total	7,028,000	5,593,000
Fixed Income Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Pension plan assets, Total	$ 3,120,000	$ 3,054,000