Investments (Details 8) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Asset derivatives:
Derivatives Asset, Net Amount	$ 8,694	$ 2,501
Free-standing derivatives [Member]
Asset derivatives:
Derivatives Asset, Gross Amounts	8,694	2,501
Derivatives Asset, Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Derivatives Asset, Net Amounts of Assets Presented in the Consolidated Balance Sheet	8,694	2,501
Derivatives Asset, Gross Amounts Not Offset in the Consolidated Balance Sheet, Financial Instruments	0	0
Derivatives Asset, Gross Amounts Not Offset in the Consolidated Balance Sheet, Cash Collateral Received	8,824	2,617
Derivatives Asset, Net Amount	$ (130)	$ (116)