Employee Benefits - Fair Value of Plan Assets (Details) - Pension Benefits - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	$ 283,940	$ 248,735	$ 199,466
Fixed maturity securities - corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	21,683	21,718
Redeemable preferred stock
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	4,633	3,534
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	178,766	149,413
Core plus bond separate account fund
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	23,916	26,266
U.S. property separate account fund
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	27,328	22,269
U.S. property separate account fund | Level 3
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	27,328	22,269	$ 22,114
Arbitrage fund
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	10,588	9,873
Recurring
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	271,967	237,333
Recurring | Level 1
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	188,452	157,207
Recurring | Level 2
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	56,187	57,857
Recurring | Level 3
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	27,328	22,269
Recurring | Fixed maturity securities - corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	21,683	21,718
Recurring | Fixed maturity securities - corporate bonds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	0	0
Recurring | Fixed maturity securities - corporate bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	21,683	21,718
Recurring | Fixed maturity securities - corporate bonds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	0	0
Recurring | Redeemable preferred stock
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	4,633	3,534
Recurring | Redeemable preferred stock | Level 1
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	4,633	3,534
Recurring | Redeemable preferred stock | Level 2
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	0	0
Recurring | Redeemable preferred stock | Level 3
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	0	0
Recurring | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	178,766	149,413
Recurring | Equity securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	178,766	149,413
Recurring | Equity securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	0	0
Recurring | Equity securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	0	0
Recurring | Core plus bond separate account fund
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	23,916	26,266
Recurring | Core plus bond separate account fund | Level 1
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	0	0
Recurring | Core plus bond separate account fund | Level 2
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	23,916	26,266
Recurring | Core plus bond separate account fund | Level 3
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	0	0
Recurring | U.S. property separate account fund
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	27,328	22,269
Recurring | U.S. property separate account fund | Level 1
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	0	0
Recurring | U.S. property separate account fund | Level 2
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	0	0
Recurring | U.S. property separate account fund | Level 3
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	27,328	22,269
Recurring | Arbitrage fund
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	10,588	9,873
Recurring | Arbitrage fund | Level 1
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	0	0
Recurring | Arbitrage fund | Level 2
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	10,588	9,873
Recurring | Arbitrage fund | Level 3
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	0	0
Recurring | Money market funds
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	5,053	4,260
Recurring | Money market funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	5,053	4,260
Recurring | Money market funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	0	0
Recurring | Money market funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Assets measured at fair value	$ 0	$ 0