Postretirement Benefits - Asset Allocation (Details) - Employee pension plan - Qualified Plan - Funded Plan	Dec. 31, 2022	Dec. 31, 2021
Target asset allocation for the portfolio:
Total plan assets	100.00%	100.00%
Actual asset allocation for the portfolio:
Total plan assets	100.00%	100.00%
Total equity securities
Target asset allocation for the portfolio:
Total plan assets	45.00%	45.00%
Actual asset allocation for the portfolio:
Total plan assets	46.00%	45.00%
U.S. equity securities
Target asset allocation for the portfolio:
Total plan assets	27.00%	27.00%
Actual asset allocation for the portfolio:
Total plan assets	27.00%	27.00%
U.S. small capitalization core equity
Target asset allocation for the portfolio:
Total plan assets	100.00%
Non-U.S. equity securities
Target asset allocation for the portfolio:
Total plan assets	18.00%	18.00%
Actual asset allocation for the portfolio:
Total plan assets	19.00%	18.00%
International small capitalization risk controlled equity
Target asset allocation for the portfolio:
Total plan assets	11.00%
International emerging markets equity
Target asset allocation for the portfolio:
Total plan assets	20.00%
International risk controlled equity
Target asset allocation for the portfolio:
Total plan assets	69.00%
Debt securities
Target asset allocation for the portfolio:
Total plan assets	54.00%	54.00%
Actual asset allocation for the portfolio:
Total plan assets	53.00%	54.00%
U.S. Treasury Strips
Target asset allocation for the portfolio:
Total plan assets	58.00%
U.S. corporate bonds with an emphasis on long duration bonds rated A or better
Target asset allocation for the portfolio:
Total plan assets	42.00%
Other
Target asset allocation for the portfolio:
Total plan assets	1.00%	1.00%
Actual asset allocation for the portfolio:
Total plan assets	1.00%	1.00%