Investments (Categories Of Net Investment Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Total investment income	$ 533,395	$ 649,466	$ 682,254
Investment expenses	(17,717)	(23,249)	(25,825)
Net investment income	515,678	626,217	656,429
Fixed maturity securities
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Total investment income	419,347	486,165	522,309
Equity securities
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Total investment income	25,161	29,957	28,014
Commercial mortgage loans on real estate
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Total investment income	41,669	72,658	73,959
Policy loans
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Total investment income	2,577	2,478	2,939
Short-term investments
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Total investment income	5,508	2,033	1,950
Other investments
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Total investment income	21,671	37,759	34,527
Cash and cash equivalents
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Total investment income	$ 17,462	$ 18,416	$ 18,556