General (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Potentially dilutive securities (in shares)	0	82,000	0	73,000
Common stock dividends (in dollars per share)	$ 0.6275	$ 0.6250	$ 1.8825	$ 1.8750
Deferred policy acquisition cost amortization	$ 150,929,000	$ 142,295,000	$ 447,971,000	$ 424,799,000
Advertising expenses	12,500,000	11,800,000	36,100,000	34,300,000
Reinsurance policy, amount of coverage			590,000,000
Reinsurance policy, amount retained			40,000,000
Ceded premiums earned	13,000,000	9,000,000	44,000,000	34,000,000
Policyholder benefits and claims incurred, ceded	1,000,000	14,000,000	(51,000,000)	13,000,000
Revenue from contract with customer	4,200,000	4,000,000.0	12,500,000	12,300,000
Cost of goods and services sold	2,500,000	$ 2,200,000	7,800,000	$ 7,600,000
Contract with customer, asset	0		0		$ 0
Contract with customer, liability	0		0		0
Revenue, remaining performance obligation	$ 0		$ 0		$ 0