General (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Condensed Balance Sheet Statements, Captions [Line Items]
Potentially dilutive securities (in shares)	68,000	0
Common stock dividends (in dollars per share)	$ 0.6300	$ 0.6275
Deferred policy acquisition cost amortization	$ 156,533,000	$ 148,413,000
Advertising expenses	11,700,000	13,600,000
Reinsurance retention policy, excess retention, amount reinsured		600,000,000
Reinsurance policy, amount retained	40,000,000
Ceded premiums earned	14,000,000	15,000,000
Policyholder benefits and claims incurred, ceded	(1,000,000)	(58,000,000)
Revenue from contract with customer	4,700,000	4,200,000
Cost of goods and services sold	3,000,000.0	2,700,000
Contract with customer, asset	0		$ 0
Contract with customer, liability	0		0
Revenue, remaining performance obligation	0		0
Capitalized implementation costs for cloud computing	5,500,000		4,400,000
Capitalized contract cost, accumulated amortization	(500,000)		(300,000)
Capitalized contract cost, amortization expense	200,000
Cumulative effect of new accounting principle in period of adoption	(1,623,444,000)	(1,719,294,000)	(1,799,502,000)
Uncollectible or written off accrued interest receivables	0	0
Accounting Standards Update 2016-13 [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Increase (decrease) in accrued interest receivable, net	0
Retained Earnings [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cumulative effect of new accounting principle in period of adoption	$ (1,524,581,000)	$ (1,620,799,000)	(1,700,674,000)	$ (1,519,658,000)
Retained Earnings [Member] | Cumulative Effect, Period Of Adoption, Adjustment [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cumulative effect of new accounting principle in period of adoption			$ 2,014,000	$ 0