Long Term Subordinated Notes (Narrative) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Redemption date	May 01, 2047
Long Term Subordinated Notes [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate	6.60%	6.60%
Maturity Date	May 01, 2067
Percentage of principal amount required for redemption	100.00%
Outstanding debt reduction	$ 161,441
Long Term Subordinated Notes [Member] | Minimum [Member]
Debt Instrument [Line Items]
Applicable spread on treasury rate	0.25%
Long Term Subordinated Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Applicable spread on treasury rate	0.50%
Fixed Rate Interest Period [Member] | Long Term Subordinated Notes [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate	6.60%
Interest payment commencement date	Nov. 15, 2007
Interest basis, term of LIBOR rate	3 months
Interest basis, 3 month LIBOR plus number of basis points, reset quarterly	2.385%
Right to defer interest on one or more occasions for up to number of consecutive years	10 years
Fixed Rate Interest Period [Member] | Long Term Subordinated Notes [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest payment date	May 3, 2007
Fixed Rate Interest Period [Member] | Long Term Subordinated Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest payment date	May 14, 2017
Floating Rate Interest Period [Member] | Long Term Subordinated Notes [Member]
Debt Instrument [Line Items]
Right to defer interest on one or more occasions for up to number of consecutive years	10 years
5.4% Senior notes due 10/15/2014 [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate	5.40%
Maturity Date	Oct. 15, 2014
4.868% Senior notes due 6/1/2044 [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate	4.868%	4.868%
Maturity Date	Jun. 01, 2044