Income Taxes - Deferred Taxes and NOL (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax asset
Deferred acquisition costs	$ 0	$ 0
Policyholder dividends	5,244	8,583
Net operating loss carryforward	32,662	96,693
Pension plan accrued benefit liability	51,289	83,562
Experience rated refunds	9,988	6,654
Tax credits	169,692	168,597
Other	13,848	19,592
Total deferred taxes	282,723	383,681
Deferred tax liability
Policyholder reserves	146,294	278,632
Deferred acquisition costs	20,405	28,071
Investment assets	185,940	233,583
Goodwill	23,287	35,306
Other	0	0
Total deferred taxes	375,926	$ 575,592
Subsidiary | Federal
Federal net operating loss carry forwards generated by a subsidiary
2023	65,209
2028	2,215
Total	$ 67,424