Fair Value (Narrative) (Details)	12 Months Ended				12 Months Ended
	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2005 security	Dec. 31, 2001 security	Dec. 31, 2014 Standard & Poor's 500 Index [Member] USD ($) security	Dec. 31, 2014 FTSE 100 Index [Member] USD ($) security	Dec. 31, 2014 FTSE 100 Index [Member] GBP (£)	Dec. 31, 2014 Fair Value [Member] Standard & Poor's 500 Index [Member] USD ($)	Dec. 31, 2014 Fair Value [Member] FTSE 100 Index [Member] USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of public equity portfolio	$ 196,980,000	$ 174,628,000
Notional Amount of Price Risk Derivatives					22,530,000	6,706,000		38,063,000	8,959,000
Number of equity index put option contracts			7	7	6	1	1
Estimates The Probability Of Equity Index Put Option Contract Strike Price On The Exercise Date					19.00%	44.00%	44.00%
Equity Index Put Option Contract, Maximum Amount Payable					0	0
Theoretical Maximum Payout Discount Factor					3.00%	3.00%	3.00%
Present Value Of Theoretical Maximum Payouts					420,013	43,334,000
Settlement Amount If Contracts Had Expired					0	0
Transfers between level 1 and 2	0
Transfers from level 3	51,101,000	46,384,000
Equity Index					$ 2,058.90		£ 6,566.10