Investments (Significant Assumptions in Determining Credit Loss Component of Other Than Temporary Impairment on Residential Mortgage Backed Securities) (Details) - Residential Mortgage Backed Securities [Member]	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Prime Sector [Member] | Vintage Year 2005 [Member] | Minimum [Member]
Schedule of Available-for-sale Securities [Line Items]
Discount rate	7.70%
Default rate	14.00%
Loss severity	50.00%
Prime Sector [Member] | Vintage Year 2005 [Member] | Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Discount rate	7.70%
Default rate	14.00%
Loss severity	50.00%
Prime Sector [Member] | Vintage Year 2006 [Member] | Minimum [Member]
Schedule of Available-for-sale Securities [Line Items]
Discount rate	7.30%	6.50%
Default rate	13.00%	14.00%
Loss severity	50.00%	40.00%
Prime Sector [Member] | Vintage Year 2006 [Member] | Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Discount rate	7.30%	6.50%
Default rate	13.00%	14.00%
Loss severity	50.00%	40.00%
Prime Sector [Member] | Vintage Year 2007 [Member] | Minimum [Member]
Schedule of Available-for-sale Securities [Line Items]
Discount rate	6.20%	5.80%
Default rate	18.00%	15.00%
Loss severity	50.00%	45.00%
Prime Sector [Member] | Vintage Year 2007 [Member] | Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Discount rate	6.40%	7.00%
Default rate	31.00%	21.00%
Loss severity	55.00%	55.00%
Alt-A Sector [Member] | Vintage Year 2005 [Member] | Minimum [Member]
Schedule of Available-for-sale Securities [Line Items]
Discount rate	7.40%	5.60%
Default rate	11.00%	99.00%
Loss severity	60.00%	2.00%
Alt-A Sector [Member] | Vintage Year 2005 [Member] | Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Discount rate	7.40%	5.60%
Default rate	11.00%	99.00%
Loss severity	60.00%	2.00%