Benefit Plans - Fair Value of Plan Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	$ 391,555	$ 411,245
Pension Plan | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	37,018	31,249
Pension Plan | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	354,537	379,996
Pension Plan | Domestic Mutual Funds
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	4,071	4,842
Pension Plan | Domestic Mutual Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	4,071	4,842
Pension Plan | Domestic Mutual Funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	0	0
Pension Plan | Corporate Bonds
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	221,033	231,190
Pension Plan | Corporate Bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	0	0
Pension Plan | Corporate Bonds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	221,033	231,190
Pension Plan | U.S. Government Securities
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	32,947	26,407
Pension Plan | U.S. Government Securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	32,947	26,407
Pension Plan | U.S. Government Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	0	0
Pension Plan | Municipal Bonds
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	20,093	32,891
Pension Plan | Municipal Bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	0	0
Pension Plan | Municipal Bonds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	20,093	32,891
Pension Plan | Foreign Bonds
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	34,103	33,368
Pension Plan | Foreign Bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	0	0
Pension Plan | Foreign Bonds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	34,103	33,368
Pension Plan | Pooled Equity Accounts
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	79,308	82,547
Pension Plan | Pooled Equity Accounts | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	0	0
Pension Plan | Pooled Equity Accounts | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	79,308	82,547
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	140,839	119,024	$ 99,590
Other Postretirement Benefit Plan | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	140,839	119,024
Other Postretirement Benefit Plan | Domestic Mutual Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	112,770	91,454
Other Postretirement Benefit Plan | International Mutual Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan Assets at Fair Value	$ 28,069	$ 27,570