Employee Benefit Plans - Fair Value of Plan Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	$ 78,661	$ 69,308	$ 59,737
Pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	78,661	69,308
Pension | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	41,009	35,317
Pension | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	37,652	33,991
Pension | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | U.S. equities, Large cap
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	20,960	17,698
Pension | U.S. equities, Large cap | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | U.S. equities, Large cap | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	20,960	17,698
Pension | U.S. equities, Large cap | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | U.S. equities, Medium cap
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	4,024	3,404
Pension | U.S. equities, Medium cap | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | U.S. equities, Medium cap | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	4,024	3,404
Pension | U.S. equities, Medium cap | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | U.S. equities, Small cap
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	3,301	2,720
Pension | U.S. equities, Small cap | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	1,365	1,360
Pension | U.S. equities, Small cap | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	1,936	1,360
Pension | U.S. equities, Small cap | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Non-U.S. equities, Large cap
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	16,183	12,919
Pension | Non-U.S. equities, Large cap | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	16,183	12,919
Pension | Non-U.S. equities, Large cap | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Non-U.S. equities, Large cap | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Non-U.S. equities, Emerging markets
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	4,759	4,060
Pension | Non-U.S. equities, Emerging markets | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	4,759	4,060
Pension | Non-U.S. equities, Emerging markets | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Non-U.S. equities, Emerging markets | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Fixed-income securities, Money markets
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	2,163	3,381
Pension | Fixed-income securities, Money markets | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Fixed-income securities, Money markets | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	2,163	3,381
Pension | Fixed-income securities, Money markets | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Fixed-income securities, U.S. bonds
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	14,648	13,569
Pension | Fixed-income securities, U.S. bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	11,067	10,172
Pension | Fixed-income securities, U.S. bonds | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	3,581	3,397
Pension | Fixed-income securities, U.S. bonds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Fixed-income securities, Non-U.S. bonds
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	7,635	6,806
Pension | Fixed-income securities, Non-U.S. bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	7,635	6,806
Pension | Fixed-income securities, Non-U.S. bonds | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Fixed-income securities, Non-U.S. bonds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Fixed-income securities, Real estate
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	3,417	3,395
Pension | Fixed-income securities, Real estate | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Fixed-income securities, Real estate | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	3,417	3,395
Pension | Fixed-income securities, Real estate | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Fixed-income securities, Common/collective trusts
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	1,571	1,356
Pension | Fixed-income securities, Common/collective trusts | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0	0
Pension | Fixed-income securities, Common/collective trusts | Significant Observable Inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	1,571	1,356
Pension | Fixed-income securities, Common/collective trusts | Significant Unobservable Inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	$ 0	$ 0