Summary of Significant Accounting Policies, Master Settlement Agreement (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Master Settlement Agreement [Abstract]
Term for restricted withdrawal of principal from MSA escrow account	25 years
Fair Value of MSA Escrow Account [Abstract]
Cost	$ 32,073	$ 32,073
Gross unrealized gains	5	4
Gross unrealized losses	(1,841)	(357)
Estimated fair value	30,237	31,720
Maturities of U.S. Governmental Agency Obligations [Abstract]
Less than one year	0
One to five years	7,443
Five to ten years	20,001
Greater than ten years	956
Total	28,400
Master Settlement Agreement Escrow Account by Sales Year [Abstract]
1999	211	211
2000	1,017	1,017
2001	1,673	1,673
2002	2,271	2,271
2003	4,249	4,249
2004	3,714	3,714
2005	4,553	4,553
2006	3,847	3,847
2007	4,167	4,167
2008	3,364	3,364
2009	1,619	1,619
2010	406	406
2011	193	193
2012	199	199
2013	173	173
2014	143	143
2015	101	101
2016	91	91
2017	82	82
Total	32,073	32,073
Cash and Cash Equivalents [Member]
Fair Value of MSA Escrow Account [Abstract]
Cost	3,673	12,155
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Estimated fair value	3,673	12,155
U. S. Governmental Agency Obligations [Member] | Unrealized Position less than 12 Months [Member]
Fair Value of MSA Escrow Account [Abstract]
Cost	21,452	19,918
Gross unrealized gains	5	4
Gross unrealized losses	(1,145)	(357)
Estimated fair value	20,312	19,565
U. S. Governmental Agency Obligations [Member] | Unrealized Position more than 12 Months [Member]
Fair Value of MSA Escrow Account [Abstract]
Cost	6,948	0
Gross unrealized gains	0	0
Gross unrealized losses	(696)	0
Estimated fair value	$ 6,252	$ 0