Investments (Schedule Of Default Assumptions By Moody's Rating Categories) (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Percentage of mortgage-backed securities represented by investments in US government agency bonds	81.00%	83.00%
Investment Grade | Aaa - Bbb | Minimum
Financing Receivable, Recorded Investment [Line Items]
1-in-100 Year Default Rate	0.00%
Historical Mean Default Rate	0.00%
Investment Grade | Aaa - Bbb | Maximum
Financing Receivable, Recorded Investment [Line Items]
1-in-100 Year Default Rate	1.30%
Historical Mean Default Rate	0.30%
Below Investment Grade | Ba
Financing Receivable, Recorded Investment [Line Items]
1-in-100 Year Default Rate	4.90%
Historical Mean Default Rate	1.10%
Below Investment Grade | B
Financing Receivable, Recorded Investment [Line Items]
1-in-100 Year Default Rate	12.70%
Historical Mean Default Rate	3.40%
Below Investment Grade | Caa - C
Financing Receivable, Recorded Investment [Line Items]
1-in-100 Year Default Rate	50.20%
Historical Mean Default Rate	13.10%