Income Taxes - Reconciliation of income taxes at the statutory rate to the provision for income taxes (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Earnings before income taxes (“EBT”)	$ 304	$ 264
Income taxes at statutory rate	64	55
Effect of ESOP dividend paid deduction	(2)	(3)
Effect of stock-based compensation	(2)	(2)
Effect of tax exempt interest	(1)	(1)
Effect of dividends received deduction	0	(1)
Effect of nondeductible expenses	2	3
Effect of foreign operations	0	2
Effect of other income	1	(1)
Provision for income taxes as shown on the Statement of Earnings	$ 62	$ 52
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Income taxes at statutory rate as a percentage of EBT	21.00%	21.00%
Effect of ESOP dividend paid deduction as a percentage of EBT	(1.00%)	(1.00%)
Effect of stock-based compensation as a percentage of EBT	(1.00%)	(1.00%)
Effect of tax exempt interest as a percentage of EBT	0.00%	0.00%
Effect of dividends received deduction as a percentage of EBT	0.00%	0.00%
Effect of nondeductible expenses as a percentage of EBT	1.00%	1.00%
Effect of foreign operations as a percentage of EBT	0.00%	1.00%
Effect of other income tax reconciliation as a percentage of EBT	0.00%	(1.00%)
Provision for income taxes as shown on the Statement of Earnings as a percentage of EBT	20.00%	20.00%

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to deduction for dividend.

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Percentage of difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operation, attributable to nondeductible expense for share-based payment arrangement.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to deduction for dividend paid to employee stock ownership plan.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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The net result for the period of deducting operating expenses from operating revenues.

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