Organization and Basis of Presentation - Summary of Financial Securities (Details) - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Equity securities:
Gross Unrealized Gain (Loss)	$ 2,215,000	$ 4,280,000
Carrying Value	2,700,000		$ 3,600,000
Held to maturity
Equity and Debt Securities, Amortized Cost	129,390,000		140,649,000
Equity and Debt Securities, Gross Unrealized Gain (Loss)	5,581,000		3,544,000
Equity and Debt Securities, Marketable Securities	134,971,000		144,193,000
Equity and Debt Securities, Allowance for Credit Loss	13,644,000		0
Investment funds - debt securities
Equity securities:
Amortized Cost/Cost	31,127,000		29,588,000
Gross Unrealized Gain (Loss)	1,135,000		544,000
Carrying Value	32,262,000		30,132,000
Common stock and stock funds
Equity securities:
Amortized Cost/Cost	67,636,000		34,941,000
Gross Unrealized Gain (Loss)	4,551,000		2,927,000
Carrying Value	72,187,000		37,868,000
U.S. treasury securities
Available for sale
Amortized Cost/Cost			2,421,000
Gross Unrealized Gain (Loss)			13,000
Carrying Value			2,434,000
Investment-grade unsecured debt
Available for sale
Amortized Cost/Cost	1,049,000		1,048,000
Gross Unrealized Gain (Loss)	(105,000)		60,000
Carrying Value	944,000		1,108,000
Allowance for Credit Losses	0
Mortgage backed security
Held to maturity
Amortized Cost/Cost	29,578,000		72,651,000
Gross Unrealized Gain (Loss)	0		0
Carrying Value	29,578,000		$ 72,651,000
Allowance for Credit Losses	$ 13,644,000