Organization and Basis of Presentation - Summary of Financial Securities (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Equity securities:
Gross Unrealized Gain (Loss)	$ 4,280	$ 426
Carrying Value	4,900		$ 6,700
Held to maturity
Equity and Debt Securities, Amortized Cost	214,858		211,960
Equity and Debt Securities, Gross Unrealized Gain (Loss)	2,036		(2,415)
Equity and Debt Securities, Marketable Securities	216,894		209,545
Investment funds - debt securities [Member]
Equity securities:
Amortized Cost/Cost	27,883		31,934
Gross Unrealized Gain (Loss)	576		(568)
Carrying Value	28,459		31,366
Common stock and stock funds [Member]
Equity securities:
Amortized Cost/Cost	37,123		39,731
Gross Unrealized Gain (Loss)	1,465		(1,671)
Carrying Value	38,588		38,060
Investment funds - U.S. treasuries [Member]
Available for sale
Amortized Cost/Cost	4,915		8,983
Gross Unrealized Gain (Loss)	(15)		(31)
Carrying Value	4,900		8,952
Investment-grade unsecured bonds [Member]
Available for sale
Amortized Cost/Cost	1,048		4,125
Gross Unrealized Gain (Loss)	10		(145)
Carrying Value	1,058		3,980
Mortgage backed securities [Member]
Held to maturity
Amortized Cost/Cost	143,889		127,187
Gross Unrealized Gain (Loss)	0		0
Carrying Value	$ 143,889		$ 127,187

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