Investments Investments (Components Of Restricted Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Components Of Restricted Assets [Line Items]
Restricted assets	$ 4,783,202	$ 5,596,401
Held In Trust Or On Deposit [Member]
Components Of Restricted Assets [Line Items]
Restricted assets	4,037,458	4,961,061
Cash And Cash Equivalents And Securities Pledged As Collateral [Member]
Components Of Restricted Assets [Line Items]
Restricted assets	$ 745,744	$ 635,340