Fair Value ( Assets and Liabilities Measured - Quantitative Information) (Details) - Fair Value, Inputs, Level 3 [Member]	Mar. 31, 2019	Dec. 31, 2018
Measurement Input, Mortality Rate [Member] | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.0002	0.0002
Measurement Input, Mortality Rate [Member] | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.1131	0.1100
Measurement Input, Lapse Rate [Member] | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.0025	0.0025
Measurement Input, Lapse Rate [Member] | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.1600	0.1600
Measurement Input, Utilization Rate [Member] | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.0000	0.0000
Measurement Input, Utilization Rate [Member] | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.2500	0.2500
Measurement Input, Withdrawal Rate [Member] | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.0025	0.0025
Measurement Input, Withdrawal Rate [Member] | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.1000	0.1000
Measurement Input, Long Term Equity Volatilities [Member] | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.1650	0.1650
Measurement Input, Long Term Equity Volatilities [Member] | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.2200	0.2200
Measurement Input, Entity Credit Risk [Member] | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.0131	0.0191
Measurement Input, Entity Credit Risk [Member] | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Liability, Measurement Input	0.0245	0.0266