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Short-Term and Long-Term Borrowings - Narrative (Details) - USD ($)	Mar. 28, 2024	Sep. 30, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Long-term debt		$ 947,000,000	$ 827,000,000
Debt instrument, redemption price, percentage of principal amount redeemed (as a percent)	10.00%
Debt instrument, redemption price, percentage (as a percent)	100.00%
Maximum
Debt Instrument [Line Items]
Debt to total capitalization ratio		0.60
Minimum
Debt Instrument [Line Items]
Interest and dividend coverage ratio		1.50
Series 2024A Senior Unsecured Notes
Debt Instrument [Line Items]
Long-term debt		$ 60,000,000	0
Interest rate (as a percent)		5.48%
Series 2024B Senior Unsecured Notes
Debt Instrument [Line Items]
Long-term debt		$ 60,000,000	$ 0
Interest rate (as a percent)		5.77%
Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 120,000,000
Senior Notes | Series 2024A Senior Unsecured Notes
Debt Instrument [Line Items]
Long-term debt	$ 60,000,000
Interest rate (as a percent)	5.48%
Senior Notes | Series 2024B Senior Unsecured Notes
Debt Instrument [Line Items]
Long-term debt	$ 60,000,000
Interest rate (as a percent)	5.77%

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