Investments (Details 6) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Asset derivatives:
Derivatives Asset, Net Amount	$ 1,946	$ 2,458
Free-standing derivatives [Member]
Asset derivatives:
Derivatives Asset, Gross Amounts	1,946	2,458
Derivatives Asset, Gross Amounts Offset in the Consolidated Balance Sheet	0	0
Derivatives Asset, Net Amounts of Assets Presented in the Consolidated Balance Sheet	1,946	2,458
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	2,117	1,955
Derivatives Asset, Net Amount	$ (171)	$ 503