Junior Subordinated Interest Deferrable Debentures (Key Information) (Details) - USD ($)		9 Months Ended
	Jul. 01, 2023	Sep. 30, 2023	Dec. 31, 2022
Junior subordinated interest deferrable debentures, major types of business trusts
Junior subordinated deferrable interest debentures		$ 108,868,000	$ 134,642,000
Trust IX
Junior subordinated interest deferrable debentures, major types of business trusts
Junior subordinated deferrable interest debentures		$ 41,238,000
Interest rate (as a percent)		7.15%
Interest rate index		LIBOR
Spread on interest rate index (as a percent)		1.62%
Trust X
Junior subordinated interest deferrable debentures, major types of business trusts
Junior subordinated deferrable interest debentures		$ 21,021,000
Interest rate (as a percent)		7.28%
Interest rate index		SOFR
Spread on interest rate index (as a percent)		1.65%
Trust XI
Junior subordinated interest deferrable debentures, major types of business trusts
Junior subordinated deferrable interest debentures		$ 25,990,000
Interest rate (as a percent)		7.15%
Interest rate index		LIBOR
Spread on interest rate index (as a percent)		1.62%
Trust XII
Junior subordinated interest deferrable debentures, major types of business trusts
Junior subordinated deferrable interest debentures		$ 20,619,000
Interest rate (as a percent)		7.12%
Interest rate index		SOFR
Spread on interest rate index (as a percent)		1.45%
Capital and Common Securities
Junior subordinated interest deferrable debentures, major types of business trusts
Spread on interest rate index (as a percent)	0.26%