Postretirement Benefits - Projected and Accumulated Benefit Obligation (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Pension Plan with Project Benefit Obligation in Excess of Plan Assets
Projected benefit obligation	$ 883,814	$ 1,272,654
Plan assets	829,866	1,140,243
Supplemental employee retirement plan (SERP) \| Nonqualified Plan \| Unfunded plan
Plan with Accumulated Benefit Obligation in Excess of Plan Assets
Accumulated benefit obligation	21,577	29,190
Plan assets	$ 0	$ 0

Amount of plan asset for defined benefit pension plan with projected benefit obligation in excess of plan assets.

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- Definition

Amount of projected benefit obligation for defined benefit pension plan with projected benefit obligation in excess of plan assets.

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Amount of accumulated benefit obligation for defined benefit plan with accumulated benefit obligation in excess of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount of plan asset for defined benefit plan with accumulated benefit obligation in excess of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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