Investments (Fair Value Below Amortized Cost of Gross Unrealized Losses for Fixed Maturity and Equity Securities) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Gross unrealized losses with number of securities [Line Items]
Gross Unrealized Losses	$ 452,058	$ 134,919
% of Total	100.00%	100.00%
Less than 20%
Gross unrealized losses with number of securities [Line Items]
Gross Unrealized Losses	$ 363,451	$ 111,965
% of Total	80.40%	83.00%
20% or more for less than six months
Gross unrealized losses with number of securities [Line Items]
Gross Unrealized Losses	$ 72,884	$ 13,698
% of Total	16.10%	10.10%
20% or more for six months or greater
Gross unrealized losses with number of securities [Line Items]
Gross Unrealized Losses	$ 15,723	$ 9,256
% of Total	3.50%	6.90%