Investments (Real Estate) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Jan. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Other long-term investments	$ 62,037			$ 56,851
Real Estate
Debt Securities, Available-for-sale [Line Items]
Other long-term investments	34,700			$ 35,700
Operating income from real estate	$ 2,100	$ 1,700
Ozark National Life Insurance Company | Real Estate
Debt Securities, Available-for-sale [Line Items]
Other long-term investments			$ 4,300