Long Term Subordinated Notes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Percentage of principal amount required for redemption	100.00%
Long Term Subordinated Debt [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate	6.60%	6.60%
Percentage of principal amount required for redemption	100.00%
Outstanding debt reduction	$ 161,441
Debt instrument, maturity date	May 01, 2067
Long Term Subordinated Debt [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Applicable spread on treasury rate	0.25%
Long Term Subordinated Debt [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Applicable spread on treasury rate	0.50%
Fixed Rate Interest Period [Member] \| Long Term Subordinated Debt [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Interest Rate Period, Beginning Date	May 03, 2007
Fixed Rate Interest Period [Member] \| Long Term Subordinated Debt [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Interest Rate Period, Ending Date	May 14, 2017
Right to defer interest on one or more occasions for up to number of consecutive years	10 years
Floating Rate Interest Period [Member] \| Long Term Subordinated Debt [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Right to defer interest on one or more occasions for up to number of consecutive years	10 years
Senior Notes 5.40% [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate	5.40%	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%	4.868%
Debt instrument, maturity date	Jun. 01, 2044
Subordinated Notes 6.6% [Member]
Debt Instrument [Line Items]
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
Subordinated Notes 6.6% [Member] \| Long Term Subordinated Debt [Member]
Debt Instrument [Line Items]
Interest payment commencement date	May 15, 2017
Floating rate terms	interest will be based on the 3 month LIBOR plus 238.5 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 ten consecutive years
Interest basis, 3 month LIBOR plus number of basis points, reset quarterly	2.385%

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

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Date the debt agreement requires the first payment to be made, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
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Contractual interest rate for funds borrowed, under the debt agreement.

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

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Percentage of principal amount of debt redeemed.

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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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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