Junior Subordinated Deferrable Interest Debentures (Key Information) (Details) - USD ($)	6 Months Ended
Jun. 30, 2022	Dec. 31, 2021
Junior subordinated interest deferrable debentures, major types of business trusts
Junior subordinated deferrable interest debentures	$ 134,642,000	$ 134,642,000
Trust VIII
Junior subordinated interest deferrable debentures, major types of business trusts
Junior subordinated deferrable interest debentures	$ 25,774,000
Interest rate (as a percent)	4.09%
Interest rate index	LIBOR
Spread on interest rate index (as a percent)	3.05%
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)	2.59%
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)	2.94%
Interest rate index	LIBOR
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)	2.59%
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)	3.05%
Interest rate index	LIBOR
Spread on interest rate index (as a percent)	1.45%

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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- Definition

The average effective interest rate during the reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
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-Publisher FASB
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-Section 50
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- Definition

Description of the interest rate as being fixed or variable, and, if variable, identification of the index or rate on which the interest rate is based and the number of points or percentage added to that index or rate to set the rate, and other pertinent information, such as frequency of rate resets.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Including the current and noncurrent portions, the carrying value of junior subordinated long-term debt owed to unconsolidated subsidiary trusts as of the balance sheet date. Such debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets and was initially scheduled to be repaid after one year or beyond the normal operating cycle if longer.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
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