Investment Holding Level 4 Concentration of Credit Risk (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Concentration of Risk, Financial Assets, Balance Sheet Groupings [Abstract]
Fair Value, Concentration of Risk, Investments	$ 0	$ 0
Risks and Uncertainties [Abstract]
Concentration Risk, Additional Characteristic	greater than 10% of the Company's stockholders' equity	greater than 10% of the Company's stockholders' equity