Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Quantitative Information for Level 3 Inputs) (Details) $ in Thousands	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Assets, Fair Value Disclosure	$ 43,250,568	$ 41,201,556
Asset-backed Securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Assets, Fair Value Disclosure	$ 81,417	$ 77,842
Asset-backed Securities [Member] | Weighted Average [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.01	0.01
Asset-backed Securities [Member] | Maximum [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.01	0.01
Asset-backed Securities [Member] | Minimum [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.00	0.00
Corporate Debt Securities [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Assets, Fair Value Disclosure	$ 740,698	$ 642,647
Corporate Debt Securities [Member] | Weighted Average [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.01	0.01
Corporate Debt Securities [Member] | Maximum [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.05	0.05
Corporate Debt Securities [Member] | Minimum [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.00	0.00
Longevity Swap [Member] | Valuation, Income Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Assets, Fair Value Disclosure	$ 48,869	$ 47,789
Funds Withheld At Interest Embedded Derivatives [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Assets, Fair Value Disclosure	107,506	109,597
US Government Agencies Debt Securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Assets, Fair Value Disclosure	$ 17,209	$ 18,025
US Government Agencies Debt Securities [Member] | Weighted Average [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.01	0.01
US Government Agencies Debt Securities [Member] | Maximum [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.01	0.01
US Government Agencies Debt Securities [Member] | Minimum [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.00	0.00
US States and Political Subdivisions Debt Securities [Member] | Weighted Average [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.00	0.00
US States and Political Subdivisions Debt Securities [Member] | Maximum [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.00	0.00
US States and Political Subdivisions Debt Securities [Member] | Minimum [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.00	0.00
Foreign Government Debt [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Assets, Fair Value Disclosure	$ 5,066	$ 5,006
Equity Securities [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Assets, Fair Value Disclosure	$ 30,294	$ 25,007
Equity Securities [Member] | Weighted Average [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Equity Securities, FV-NI, Measurement Input	0.04	0.04
Equity Securities [Member] | Maximum [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Equity Securities, FV-NI, Measurement Input	0.04	0.04
Equity Securities [Member] | Minimum [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Equity Securities, FV-NI, Measurement Input	0.04	0.04
Embedded Derivatives In Indexed Annuity [Member] | Valuation, Income Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Financial and Nonfinancial Liabilities, Fair Value Disclosure	$ 754,171	$ 776,940
Embedded Derivatives In Indexed Annuity [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.02	0.02
Embedded Derivatives In Indexed Annuity [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.04	0.04
Embedded Derivatives In Indexed Annuity [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.02	0.02
Embedded Derivatives In Variable Annuity [Member] | Valuation, Income Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Financial and Nonfinancial Liabilities, Fair Value Disclosure	$ 149,764	$ 167,925
Mortality Swap [Member] | Valuation, Income Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Financial and Nonfinancial Liabilities, Fair Value Disclosure	$ (489)	$ 369
Debt Security, Corporate, Non-US [Member] | Weighted Average [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.01	0.01
Debt Security, Corporate, Non-US [Member] | Maximum [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.01	0.01
Debt Security, Corporate, Non-US [Member] | Minimum [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.01	0.01
Measurement Input, Long-term Revenue Growth Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.13	0.13
Measurement Input, Long-term Revenue Growth Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.27	0.27
Measurement Input, Long-term Revenue Growth Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.00	0.00
Measurement Input Mortality Improvement [Member] | Longevity Swap [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.03	0.03
Measurement Input Mortality Improvement [Member] | Longevity Swap [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.10	0.10
Measurement Input Mortality Improvement [Member] | Longevity Swap [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	(0.10)	(0.10)
Measurement Input Crediting Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Weighted Average [Member] | Valuation, Income Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Asset, Measurement Input	0.02	0.02
Measurement Input Crediting Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Maximum [Member] | Valuation, Income Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Asset, Measurement Input	0.04	0.04
Measurement Input Crediting Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Minimum [Member] | Valuation, Income Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Asset, Measurement Input	0.02	0.02
Measurement Input, Counterparty Credit Risk [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Weighted Average [Member] | Valuation, Income Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Asset, Measurement Input	0.01	0.01
Measurement Input, Counterparty Credit Risk [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Maximum [Member] | Valuation, Income Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Asset, Measurement Input	0.05	0.05
Measurement Input, Counterparty Credit Risk [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Minimum [Member] | Valuation, Income Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Asset, Measurement Input	0.00	0.00
Measurement Input, Counterparty Credit Risk [Member] | Embedded Derivatives In Variable Annuity [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.01	0.01
Measurement Input, Counterparty Credit Risk [Member] | Embedded Derivatives In Variable Annuity [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.05	0.05
Measurement Input, Counterparty Credit Risk [Member] | Embedded Derivatives In Variable Annuity [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.00	0.00
Measurement Input, Withdrawal Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Weighted Average [Member] | Valuation, Income Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Asset, Measurement Input	0.03	0.03
Measurement Input, Withdrawal Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Maximum [Member] | Valuation, Income Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Asset, Measurement Input	0.05	0.05
Measurement Input, Withdrawal Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Minimum [Member] | Valuation, Income Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Asset, Measurement Input	0.00	0.00
Measurement Input, Withdrawal Rate [Member] | Embedded Derivatives In Indexed Annuity [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.03	0.03
Measurement Input, Withdrawal Rate [Member] | Embedded Derivatives In Indexed Annuity [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.05	0.05
Measurement Input, Withdrawal Rate [Member] | Embedded Derivatives In Indexed Annuity [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.00	0.00
Measurement Input, Withdrawal Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.04	0.05
Measurement Input, Withdrawal Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.07	0.07
Measurement Input, Withdrawal Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.00	0.00
Measurement Input, Lapse Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Weighted Average [Member] | Valuation, Income Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Asset, Measurement Input	0.11	0.10
Measurement Input, Lapse Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Maximum [Member] | Valuation, Income Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Asset, Measurement Input	0.35	0.35
Measurement Input, Lapse Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Minimum [Member] | Valuation, Income Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Asset, Measurement Input	0.00	0.00
Measurement Input, Lapse Rate [Member] | Embedded Derivatives In Indexed Annuity [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.11	0.10
Measurement Input, Lapse Rate [Member] | Embedded Derivatives In Indexed Annuity [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.35	0.35
Measurement Input, Lapse Rate [Member] | Embedded Derivatives In Indexed Annuity [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.00	0.00
Measurement Input, Lapse Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.05	0.05
Measurement Input, Lapse Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.25	0.25
Measurement Input, Lapse Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.00	0.00
Measurement Input, Mortality Rate [Member] | Longevity Swap [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.02	0.02
Measurement Input, Mortality Rate [Member] | Longevity Swap [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	1.00	1.00
Measurement Input, Mortality Rate [Member] | Longevity Swap [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.00	0.00
Measurement Input, Mortality Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Weighted Average [Member] | Valuation, Income Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Asset, Measurement Input	0.02	0.02
Measurement Input, Mortality Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Maximum [Member] | Valuation, Income Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Asset, Measurement Input	1.00	1.00
Measurement Input, Mortality Rate [Member] | Funds Withheld At Interest Embedded Derivatives [Member] | Minimum [Member] | Valuation, Income Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Asset, Measurement Input	0.00	0.00
Measurement Input, Mortality Rate [Member] | Embedded Derivatives In Indexed Annuity [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.02	0.02
Measurement Input, Mortality Rate [Member] | Embedded Derivatives In Indexed Annuity [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	1.00	1.00
Measurement Input, Mortality Rate [Member] | Embedded Derivatives In Indexed Annuity [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.00	0.00
Measurement Input, Mortality Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.01	0.01
Measurement Input, Mortality Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	1.00	1.00
Measurement Input, Mortality Rate [Member] | Embedded Derivatives In Variable Annuity [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Embedded Derivative Liability, Measurement Input	0.00	0.00
Measurement Input, Mortality Rate [Member] | Mortality Swap [Member] | Weighted Average [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.01	0.01
Measurement Input, Mortality Rate [Member] | Mortality Swap [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	1.00	1.00
Measurement Input, Mortality Rate [Member] | Mortality Swap [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	0.00	0.00
Measurement Input, EBITDA Multiple [Member] | Corporate Debt Securities [Member] | Weighted Average [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	5.9	6.5
Measurement Input, EBITDA Multiple [Member] | Corporate Debt Securities [Member] | Maximum [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	5.9	7.5
Measurement Input, EBITDA Multiple [Member] | Corporate Debt Securities [Member] | Minimum [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Debt Instrument, Measurement Input	5.9	5.9
Measurement Input, EBITDA Multiple [Member] | Equity Securities [Member] | Weighted Average [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Equity Securities, FV-NI, Measurement Input	8.2	7.9
Measurement Input, EBITDA Multiple [Member] | Equity Securities [Member] | Maximum [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Equity Securities, FV-NI, Measurement Input	12.3	12.3
Measurement Input, EBITDA Multiple [Member] | Equity Securities [Member] | Minimum [Member] | Valuation, Market Approach [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Equity Securities, FV-NI, Measurement Input	6.9	6.9