Investments, Securities in Continuous Unrealized Loss Position (Details)		3 Months Ended	12 Months Ended
		Mar. 31, 2018 USD ($) Security	Dec. 31, 2017 USD ($) Security
U.S. Government and Government Agencies and Authorities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, fair value		$ 4,925,360	$ 0
Less than 12 months, unrealized losses		(47,756)	0
12 months or longer, fair value		1,567,604	1,604,987
12 months or longer, unrealized losses		(111,520)	(73,530)
Total fair value		6,492,964	1,604,987
Total unrealized losses		(159,276)	(73,530)
Debt Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, fair value		40,644,440	9,732,635
Less than 12 months, unrealized losses		(812,249)	(91,757)
12 months or longer, fair value		8,031,255	12,769,304
12 months or longer, unrealized losses		(593,731)	(279,936)
Total fair value		48,675,695	22,501,939
Total unrealized losses		$ (1,405,980)	$ (371,693)
Less than 12 months, number of securities | Security		24	6
Twelve months or longer, number of securities | Security		6	6
Total number of securities | Security		30	12
Equity Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, fair value	[1]		$ 4,130,260
Less than 12 months, unrealized losses	[1]		(270,774)
12 months or longer, fair value	[1]		1,526,868
12 months or longer, unrealized losses	[1]		(241,569)
Total fair value	[1]		5,657,128
Total unrealized losses	[1]		$ (512,343)
Less than 12 months, number of securities | Security	[1]		2
Twelve months or longer, number of securities | Security	[1]		2
Total number of securities | Security	[1]		4
All Other Corporate Bonds [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, fair value		$ 35,719,080	$ 9,732,635
Less than 12 months, unrealized losses		(764,493)	(91,757)
12 months or longer, fair value		6,463,651	11,164,317
12 months or longer, unrealized losses		(482,211)	(206,406)
Total fair value		42,182,731	20,896,952
Total unrealized losses		$ (1,246,704)	$ (298,163)

[1] Effective January 1, 2018, the Company adopted ASU No. 2016-01 and equity securities are no longer classified as available-for-sale. Prior periods have not been restated to conform to the current presentation. See Note 2 to the Condensed Consolidated Financial Statements for additional information.