Business Combinations - Goodwill and Specifically Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Net goodwill as of end of year	$ 13,900	$ 13,900
Ozark National Life Insurance Company And NIS
Goodwill [Roll Forward]
Gross goodwill as of beginning of year	13,864	0
Goodwill resulting from business acquisition	0	13,864
Gross goodwill, before impairments	13,864	13,864
Accumulated impairment as of beginning of year	0	0
Current year impairments	0	0
Net goodwill as of end of year	$ 13,864	$ 13,864