Long Term Subordinated Notes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2020	Dec. 31, 2019
Long Term Subordinated Debt [Member]
Debt Instrument [Line Items]
Outstanding debt reduction	$ 161,441
Senior Notes 5.40% [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate	5.40%
Debt instrument, maturity date	Oct. 15, 2014
Senior Notes 4.868% [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate	4.868%
Debt instrument, maturity date	Jun. 01, 2044	Jun. 01, 2044
Subordinated Notes 6.6% [Member] \| Long Term Subordinated Debt [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate	6.60%
Right to defer interest, period	10 years
Reset quarterly interest rate	4.08%
Interest basis, 3 month LIBOR plus number of basis points, reset quarterly	2.385%
Percentage of principal amount required for redemption	100.00%
Outstanding debt reduction	$ 1,700
Gain on repurchase and retirement of debt	$ 502
Debt instrument, maturity date	May 01, 2067	May 01, 2067
Subordinated Notes 6.6% [Member] \| Long Term Subordinated Debt [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Interest payment date	May 3, 2007
Redemption date	May 15, 2017
Subordinated Notes 6.6% [Member] \| Long Term Subordinated Debt [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Interest payment date	May 14, 2017
Redemption date	May 01, 2047

Right To Defer Interest, Period

No definition available.

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- Definition

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

+ References

No definition available.

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- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
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Contractual interest rate for funds borrowed, under the debt agreement.

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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

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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- Definition

Description of the payment terms of the debt instrument (for example, whether periodic payments include principal and frequency of payments) and discussion about any contingencies associated with the payment.

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- Definition

End date of debt instrument redemption period, in CCYY-MM-DD format.

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- Definition

Percentage of principal amount of debt redeemed.

+ References

No definition available.

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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- Definition

The cash outflow from the repayment of long-term borrowing where a lender is placed in a lien position behind debt having a higher priority of repayment (senior) in case of liquidation of the entity's assets or underlying collateral.

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