Summary of Significant Accounting and Reporting Policies (Schedule of Amortized Cost, Unrealized Gains And Losses, And Market Value Of Investment Securities) (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Long-Term Investments:
Cost	$ 269,889,067	$ 303,467,531
Unrealized gains	1,974,255	440,807
Unrealized losses	(587,564)	(366,257)
Total	271,275,758	303,542,081
Certificates of Deposit
Short-Term Investments:
Cost	50,099,795	150,299,384
Gains	0	0
Losses	0	0
Market Value	50,099,795	150,299,384
Long-Term Investments:
Cost	3,500,000
Gains	58,808
Losses	(1,010)
Market Value	3,557,798
Asset-backed Securities
Long-Term Investments:
Cost	25,971,156
Gains	0
Losses	(180,127)
Market Value	25,791,029
Government Securities
Short-Term Investments:
Cost	58,343,911	9,186,586
Gains	99,917	0
Losses	(11,005)	(10,359)
Market Value	58,432,823	9,176,227
Long-Term Investments:
Cost	6,012,705	56,280,552
Gains	75,485	205,553
Losses	0	(2,385)
Market Value	6,088,190	56,483,720
Municipal Bonds
Long-Term Investments:
Cost	71,997,996	17,840,518
Gains	1,036,116	184,914
Losses	(395,422)	0
Market Value	72,638,690	18,025,432
Corporate Bonds
Short-Term Investments:
Cost	29,025,624	6,981,305
Gains	194,061	0
Losses	0	(13,605)
Market Value	29,219,685	6,967,700
Long-Term Investments:
Cost	22,306,130	60,659,498
Gains	509,868	50,340
Losses	0	(339,908)
Market Value	22,815,998	60,369,930
Other
Short-Term Investments:
Cost	2,631,750	2,219,688
Gains	0	0
Losses	0	0
Market Value	$ 2,631,750	2,219,688
Common Stocks
Long-Term Investments:
Cost		0
Gains		0
Losses		0
Market Value		$ 0