Investment Operations Derivative instruments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Derivative Assets	$ 34,181	$ 5,757
Derivative Liability	(76,600)	(40,808)
Derivative, Gain (Loss) on Derivative, Net	2,232	(7,162)	$ 8,007
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Asset	25,600
Net exposure to credit losses on derivatives	7,000
Equity Option | Investment Income
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	22,497	(7,749)	9,372
Embedded Derivative Financial Instruments - MODCO | Investment Income
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	2,695	(2,480)	(1,440)
Embedded Derivative Financial Instruments - Interest only Security | Investment Income
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	90	(176)	(246)
Embedded Derivative Financial Instruments | Interest sensitive product charges
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(23,050)	3,243	$ 321
Call options (reported in other investments) | Equity Option
Derivative [Line Items]
Derivative Assets	31,469	4,745
Modified coinsurance (reported in reinsurance recoverable) | Embedded Derivative Financial Instruments
Derivative [Line Items]
Derivative Asset, Assumed	2,327	157
Interest-only security (reported in fixed maturities) | Embedded Derivative Financial Instruments
Derivative [Line Items]
Derivative Assets	385	855
Indexed products (reported in liability for future policy benefits) | Embedded Derivative Financial Instruments
Derivative [Line Items]
Derivative Liability	(76,346)	(40,028)
Modified coinsurance (reported in other liabilities) | Embedded Derivative Financial Instruments
Derivative [Line Items]
Derivative Liability	$ (254)	$ (780)