Pension and Other Postretirement Plans - Defined Contribution Pension Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
National Western Life Insurance Company:
Defined Benefit Plan Disclosure [Line Items]
Additional company's matching contribution	4.00%	4.00%	4.00%
Ozark National Life Insurance Company:
Defined Benefit Plan Disclosure [Line Items]
Additional company's matching contribution	4.00%
Qualified Plan | National Western Life Insurance Company:
Defined Benefit Plan Disclosure [Line Items]
Total company contribution, 401(k) plan	$ 703	$ 755	$ 720
Qualified Plan | Ozark National Life Insurance Company:
Defined Benefit Plan Disclosure [Line Items]
Expenses related to the plan	112	125	175
Qualified Plan | NIS
Defined Benefit Plan Disclosure [Line Items]
Expenses related to the plan	15	10	17
Non-Qualified Contribution Pension Plan | National Western Life Insurance Company:
Defined Benefit Plan Disclosure [Line Items]
Total company contribution, 401(k) plan	128	143	175
Non-Qualified Contribution Pension Plan | Ozark National Life Insurance Company:
Defined Benefit Plan Disclosure [Line Items]
Expenses related to the plan	$ (75)	$ 24	$ 247