Long Term Subordinated Notes (Narrative) (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2019	Dec. 31, 2018
Long Term Subordinated Debt [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate	6.60%
Reset quarterly interest rate	4.90%
Outstanding debt reduction	$ 161,441
Fixed Rate Interest Period [Member] \| Long Term Subordinated Debt [Member]
Debt Instrument [Line Items]
Interest basis, 3 month LIBOR plus number of basis points, reset quarterly	2.385%
Floating Rate Interest Period [Member]
Debt Instrument [Line Items]
Floating rate terms	interest will be based on the 3 month LIBOR plus <font class="_mt">238.5</font> basis points, reset quarterly, payable quarterly in arrears on February 15, May 15, August 15 and November 15 of each year, subject to Holdings' right to defer interest on one or more occasions for up to <font class="_mt">ten</font> consecutive years.
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
Percentage of principal amount required for redemption	100.00%
Redemption date	May 01, 2047
Commencement date for cash tender offer for any and all of the 6.60% fixed to floating rate long term subordinated notes	Mar. 19, 2009
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
Subordinated Notes 6.6% [Member] \| Long Term Subordinated Debt [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Interest payment date	May 14, 2017

Commencement Date For Cash Tender Offer

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- Definition

Right To Defer Interest, Period

+ References

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
-SubTopic 20
-Section 50
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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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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.

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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.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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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.

+ References

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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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- 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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