Investments (Purchased Credit Impaired Investments) (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015
Certain Loans Acquired in Transfer Accounted for as Available-for-sale Debt Securities, Acquired [Abstract]
Certain Loans Acquired in Transfer Accounted for as Available-for-sale Debt Securities, Acquired, Contractually Required Payments Receivable at Acquisition		$ 7,310	$ 217,187
Certain Loans Acquired in Transfer Accounted for as Available-for-sale Debt Securities, Acquired, Cash Flows Expected to be Collected at Acquisition	[1]	5,748	179,025
Certain Loans Acquired in Transfer Accounted for as Available-for-sale Debt Securities, Acquired, at Acquisition, at Fair Value		$ 4,139	$ 137,399

[1] Represents undiscounted principal and interest cash flow expectations at the date of acquisition.