Investments (Gains And Losses Due To Changes In Fair Value Of Investments) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Gains and losses due to changes in fair value of investments	$ (70,020)	$ (12,907)	$ 8,793	$ (58,532)	$ 28,065	$ 17,608	$ 20,275	$ 21,857	$ (132,658)	$ 87,927	$ (32,805)
Fixed Maturity Securities [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Gains and losses due to changes in fair value of investments									(53,927)	50,403	(56,584)
Equity Securities [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Gains and losses due to changes in fair value of investments									(77,494)	37,486	23,722
Short-term Investments [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Gains and losses due to changes in fair value of investments									$ (1,237)	$ 38	$ 57