Employee Benefits - Schedule of the Fair Values of the Retirement Plan Assets by Asset Category (Details) - Pension Benefits - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 97,890	$ 93,638	$ 85,553
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	97,890
Cash
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,079	1,269
Cash | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,079
Equity Securities - Large Cap
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,849	1,731
Equity Securities - Large Cap | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,849
Equity Security - Mutual Funds: Mixed-Cap
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	29,802	29,336
Equity Security - Mutual Funds: Mixed-Cap | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	29,802
Equity Security - Mutual Funds: International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	28,055	23,961
Equity Security - Mutual Funds: International | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	28,055
Equity Security - Mutual Funds: Emerging Market
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,494	2,342
Equity Security - Mutual Funds: Emerging Market | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,494
Fixed Income - Mutual Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	34,611	$ 34,999
Fixed Income - Mutual Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 34,611