Summary of Significant Accounting Policies (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) segment $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Jan. 01, 2020 USD ($)
Investments
Maximum period considered for applying equity method accounting based on financial information provided by the investee	3 months
Accounts Receivable
Premiums receivable, allowance for doubtful accounts	$ 1,446	$ 1,808
Deferred Policy Acquisition Costs
Amortization expense	$ 146,013	146,573	$ 146,955
Intangible Assets
Amortization period	10 years
Intangible assets amortization expense	$ 44
Expected annual amortization expense	$ 786
Revenue Recognition
Term over which premiums are earned	1 year
Deferred revenue	$ 12,858	10,630
Advertising Costs
Advertising costs	2,399	2,232	2,311
Earnings per Weighted Average Common Share
Net income from continuing operations	46,561	130,710	138,211
Allocation for participating shares	(205)	575	636
Net income from continuing operations attributed to common shareholders	$ 46,356	$ 131,285	$ 138,847
Total weighted average common shares outstanding, including participating shares | shares	14,672,234	14,894,532	15,071,955
Less: weighted average participating shares | shares	(64,751)	(65,796)	(69,200)
Basic earnings per share denominator | shares	14,607,483	14,828,736	15,002,755
Common equivalent shares- non-vested performance stock grants | shares	103,128	96,990	116,272
Diluted earnings per share denominator | shares	14,710,611	14,925,726	15,119,027
Basic earnings per share (in dollars per share) | $ / shares	$ 3.17	$ 8.85	$ 9.25
Diluted earnings per share (in dollars per share) | $ / shares	$ 3.15	$ 8.80	$ 9.18
Antidilutive common shares | shares	0	0	0
Undistributed earnings attributable to common shareholders - basic
Net income from continuing operations attributable to common shareholders -Basic | $ / shares	$ 3.17	$ 8.85	$ 9.25
Dividends declared | $ / shares	(3.60)	(3.60)	(3.60)
Undistributed earnings | $ / shares	(0.43)	5.25	5.65
Undistributed earnings attributable to common shareholders - diluted
Net income from continuing operations attributable to common shareholders -Diluted | $ / shares	3.15	8.80	9.18
Dividends declared | $ / shares	(3.60)	(3.60)	(3.60)
Undistributed earnings | $ / shares	$ (0.45)	$ 5.20	$ 5.58
Recent Accounting Pronouncements
Retained earnings	$ 815,309	$ 821,743
Fixed maturity securities, allowance for expected credit losses	678	691		$ 2,510
Operating lease liabilities	$ 23,336	$ 27,115
Segments
Number of business segments | segment	1
Minimum
Equipment and Leasehold Improvements
Estimated useful lives	3 years
Maximum
Equipment and Leasehold Improvements
Estimated useful lives	10 years