Investments (Fair Value Below Amortized Cost of Gross Unrealized Losses for Fixed Maturity and Equity Securities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Gross unrealized losses with number of securities [Line Items]
Available-for-sale Securities, Gross Unrealized Losses	$ 627,451	$ 134,919
Percentage Of Total Gross Unrealized Losses	100.00%	100.00%
Less Than 20 Percent [Member]
Gross unrealized losses with number of securities [Line Items]
Available-for-sale Securities, Gross Unrealized Losses	$ 463,109	$ 111,965
Percentage Of Total Gross Unrealized Losses	73.80%	83.00%
More Than Or Equal To 20 Percent For Less Than Six Months [Member]
Gross unrealized losses with number of securities [Line Items]
Available-for-sale Securities, Gross Unrealized Losses	$ 142,495	$ 13,698
Percentage Of Total Gross Unrealized Losses	22.70%	10.10%
More Than Or Equal To 20 Percent For Six Months Or Greater [Member]
Gross unrealized losses with number of securities [Line Items]
Available-for-sale Securities, Gross Unrealized Losses	$ 21,847	$ 9,256
Percentage Of Total Gross Unrealized Losses	3.50%	6.90%