Investment Operations Derivative instruments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Derivative Assets	$ 16,145	$ 9,518
Derivative Liability	(15,892)	(9,430)
Derivative, Gain (Loss) on Derivative, Net	1,545	311	$ 2,064
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Asset	6,300
Other Investments [Member] | Equity Option [Member]
Derivative [Line Items]
Derivative Assets	9,360	2,331
Reinsurance Recoverable [Member] | Embedded Derivative Financial Instruments [Member]
Derivative [Line Items]
Derivative Assets	3,411	2,636
Available-for-sale Securities [Member] | Embedded Derivative Financial Instruments [Member]
Derivative [Line Items]
Derivative Assets	3,374	4,551
Contract Holder Funds [Member] | Embedded Derivative Financial Instruments [Member]
Derivative [Line Items]
Derivative Liability	(15,778)	(9,374)
Other Liabilities [Member] | Embedded Derivative Financial Instruments [Member]
Derivative [Line Items]
Derivative Liability	(114)	(56)
Investment Income [Member] | Equity Option [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	5,603	(1,904)	1,559
Investment Income [Member] | Embedded Derivative Financial Instruments - MODCO [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	716	(809)	711
Investment Income [Member] | Embedded Derivative Financial Instruments - Interest only Security [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	229	23	0
Investment Income [Member] | Amortization on Equity Options [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(5,601)	(3,122)	(1,535)
Investment Income [Member] | Proceeds on Equity Options [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	2,988	3,546	1,761
Interest sensitive product charges | Embedded Derivative Financial Instruments [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ (2,390)	$ 2,577	$ (432)