Investments (Proceeds From Sales Of Available-For-Sale Securities And The Gross Realized Gains And Gross Realized Losses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Investments, Debt and Equity Securities [Abstract]
Proceeds from sales	$ 2,568,166	$ 1,995,368	$ 2,821,177
Gross realized gains	65,097	69,184	81,921
Gross realized losses	$ 31,657	$ 10,681	$ 50,667