Employee Benefit Arrangements - Plan Assets, Allocation (Details) - Pension Plan	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Actual allocation	100.00%	100.00%
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Actual allocation	8.20%	8.20%
Equity securities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target allocation range, minimum	5.00%	7.00%
Equity securities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target allocation range, minimum	13.00%	12.00%
Large-cap domestic
Defined Benefit Plan Disclosure [Line Items]
Actual allocation	4.30%	3.70%
Small/Mid-cap domestic
Defined Benefit Plan Disclosure [Line Items]
Actual allocation	0.90%	0.80%
International Commingled Funds
Defined Benefit Plan Disclosure [Line Items]
Actual allocation	2.90%	3.20%
Other
Defined Benefit Plan Disclosure [Line Items]
Actual allocation	0.10%	0.50%
Debt securities
Defined Benefit Plan Disclosure [Line Items]
Actual allocation	85.80%	84.40%
Debt securities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target allocation range, minimum	83.00%	83.00%
Debt securities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target allocation range, minimum	87.00%	87.00%
U.S. Treasuries, short term investments, cash and futures
Defined Benefit Plan Disclosure [Line Items]
Actual allocation	2.00%	3.00%
U.S. government agencies and authorities
Defined Benefit Plan Disclosure [Line Items]
Actual allocation	4.70%	0.30%
U.S. corporate, state and municipalities
Defined Benefit Plan Disclosure [Line Items]
Actual allocation	66.80%	71.30%
Other investments, including securities pledged
Defined Benefit Plan Disclosure [Line Items]
Actual allocation	6.00%	7.40%
Other investments, including securities pledged | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target allocation range, minimum	2.00%	4.00%
Other investments, including securities pledged | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target allocation range, minimum	10.00%	8.00%
Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Actual allocation	2.90%	4.10%
Real estate
Defined Benefit Plan Disclosure [Line Items]
Actual allocation	3.10%	3.30%
Foreign securities
Defined Benefit Plan Disclosure [Line Items]
Actual allocation	12.30%	9.80%