Fair Value Measurements FV Inputs of Assets (Details) - Internal model pricing valuation - Recurring basis - Significant unobservable inputs (Level 3)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Minimum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity Volatility	15.00%	15.00%
Swap Curve	1.69%	0.75%
Lapse Rate	1.00%	1.00%
Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity Volatility	30.00%	30.00%
Swap Curve	2.54%	3.00%
Lapse Rate	15.00%	15.00%