Stockholders' Equity AOCI Reclassifications table (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net realized capital gains on sales of investments		$ 8,523		$ (7,276)		$ 599
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net		(919)		(4,998)		(1,553)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Net of Tax, Portion Attributable to Parent		(389,655)		94,392		(274,507)
reclassifications out of accumulated other comprehensive income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net realized capital gains on sales of investments		(2)		(1,832)		(255)
Change in offsets to unrealized on investments		(241)		205		274
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net				(74)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Gain (Loss), Reclassification Adjustment from AOCI, before Tax		1,892		(2,515)		(1,702)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI Attributable to Parent, before Tax		(1,653)		404		(1,683)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent		348		(85)		215
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Net of Tax, Portion Attributable to Parent		1,305		(319)		(1,468)
reclassifications out of accumulated other comprehensive income | Accumulated Net Unrealized Investment Gain (Loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net realized capital gains on sales of investments		(2)	[1]	(1,832)	[1]	(255)	[2]
Change in offsets to unrealized on investments		(241)	[1]	206	[1]	274	[2]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Gain (Loss), Reclassification Adjustment from AOCI, before Tax		0		0		0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax	[1]	(239)		2,038		19
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax	[1]	(50)		428		(4)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax	[1]	189		(1,610)		15
reclassifications out of accumulated other comprehensive income | Accumulated Other-than-Temporary Impairment
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net realized capital gains on sales of investments		0	[1]	0	[1]	0	[2]
Change in offsets to unrealized on investments	[1]	0		(1)		0
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	[1]			(74)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Gain (Loss), Reclassification Adjustment from AOCI, before Tax		0		0		0
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI for Write-down of Securities, before Tax		0	[1]	(73)	[1]	0	[2]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI for Write-down of Securities, Tax		0	[1]	15	[1]	0	[2]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI for Write-down of Securities, Net of Tax		0	[1]	(58)	[1]	0	[2]
reclassifications out of accumulated other comprehensive income | Accumulated Defined Benefit Plans Adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net realized capital gains on sales of investments		0		0		0
Change in offsets to unrealized on investments		0		0		0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Gain (Loss), Reclassification Adjustment from AOCI, before Tax		1,892	[3]	(2,515)	[4]	1,702	[3]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI for Pension and Other Postretirement Benefit Plans, before Tax	[3]	1,892		(2,515)		1,702
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI for Pension and Other Post Retirement Benefit Plans, Tax	[3]	398		(528)		219
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Gain (Loss), Reclassification Adjustment from AOCI, Net of Tax	[3]	$ (1,494)		$ 1,987		$ (1,483)

[1] See Note 2 for further information.

[2] Unrealized net investment gains (losses) relate to available-for-sale securities and include the impact of taxes, deferred acquisition costs, value of insurance in force acquired, unearned revenue reserves and policyholder liabilities. See Note 2 for further information.

[3] For descriptions of the underfunded portion of our postretirement benefit plans, see Note 8 - Other Retirement Plans, and for certain other defined benefit plans, see Note 8 - Defined Benefit Plans.

[4] For descriptions of the underfunded portion of our postretirement benefit plans, see Note 8 - Other Retirement Plans, and for certain other defined benefit plans, see Note 8 - Defined Benefit Pension Plans.