Investments (Securities Pledged) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Financial Instruments Owned and Pledged as Collateral and Associated Liabilities
Securities Pledged	$ 140,810	$ 38,421
Liabilities Supported by Pledged Collateral	143,880	40,416
Fixed maturities, available-for-sale:
Financial Instruments Owned and Pledged as Collateral and Associated Liabilities
Securities Pledged	140,810	38,421
Cash Collateral For Loaned Securities
Financial Instruments Owned and Pledged as Collateral and Associated Liabilities
Liabilities Supported by Pledged Collateral	74,976	40,416
Securities Sold under Agreements to Repurchase
Financial Instruments Owned and Pledged as Collateral and Associated Liabilities
Liabilities Supported by Pledged Collateral	$ 68,904	$ 0