Investments - Additional Information (Details)		3 Months Ended					6 Months Ended
	Jan. 02, 2018 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($) day $ / shares shares	Jun. 30, 2018 USD ($) $ / shares	Jun. 30, 2019 USD ($) day $ / shares shares	Jun. 30, 2018 USD ($) $ / shares	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jul. 24, 2018 $ / shares	Oct. 25, 2017 $ / shares
Debt Securities, Available-for-sale [Line Items]
Securities in unrealized loss positions					44		44			64
Other-than-temporary impairment loss					$ 0	$ 0	$ 75,000	$ 0
Limited liability investments					3,891,000		3,891,000			$ 4,790,000
(Gain) loss on change in fair value of limited liability investments, at fair value					2,347,000	(525,000)	6,612,000	(1,461,000)
Limited liability investments, at fair value					33,047,000		33,047,000			26,015,000
Investment impairment losses					0	0	0	0
Unfunded commitments					600,000		600,000
Investments in private companies, at adjusted cost					2,661,000		2,661,000			3,090,000
Net change in unrealized gain (loss) on private company investments					0	$ (155,000)	19,000	(155,000)
Other-than-temporary impairment loss							75,000	$ 0
Real estate investments					10,662,000		10,662,000			10,662,000
Other investments					$ 895,000		$ 895,000			2,079,000
Stock price threshold trading days | day					20		20
Threshold trading days | day					30		30
Restricted cash					$ 17,320,000		$ 17,320,000			16,959,000
Variable Interest Entity, Primary Beneficiary
Debt Securities, Available-for-sale [Line Items]
Unfunded commitments					$ 600,000		$ 600,000
Performance Share Grant Agreement
Debt Securities, Available-for-sale [Line Items]
Stock reserved for future issuances (in shares) | shares					475,000		475,000
Minimum
Debt Securities, Available-for-sale [Line Items]
Stock reserved for future issuances (in shares) | shares					100,000		100,000
Share price (in dollars per share) | $ / shares						$ 10.00		$ 10.00
Maximum
Debt Securities, Available-for-sale [Line Items]
Share price (in dollars per share) | $ / shares					$ 18		$ 18				$ 18.00
Clause 2
Debt Securities, Available-for-sale [Line Items]
Stock reserved for future issuances (in shares) | shares					125,000		125,000
Share price (in dollars per share) | $ / shares					$ 12.00		$ 12.00				12.00
Clause 1 and 2
Debt Securities, Available-for-sale [Line Items]
Stock reserved for future issuances (in shares) | shares					225,000		225,000
Clause 3
Debt Securities, Available-for-sale [Line Items]
Share price (in dollars per share) | $ / shares					$ 15		$ 15				$ 15.00
Clause 1, 2 and 3
Debt Securities, Available-for-sale [Line Items]
Stock reserved for future issuances (in shares) | shares					350,000		350,000
Management
Debt Securities, Available-for-sale [Line Items]
Share price (in dollars per share) | $ / shares												$ 7.85
Consideration received on transaction	$ 300,000
Proceeds from sale of available-for-sale debt securities								$ 300,000
Mendota
Debt Securities, Available-for-sale [Line Items]
Escrow deposit					$ 5,100,000		$ 5,100,000			5,000,000
IWS
Debt Securities, Available-for-sale [Line Items]
Restricted cash									$ 10,000,000
State and Provincial Regulatory Authorities
Debt Securities, Available-for-sale [Line Items]
Restricted cash equivalents					200,000		200,000			200,000
Restricted cash					1,900,000		1,900,000			1,900,000
Third Parties
Debt Securities, Available-for-sale [Line Items]
Restricted cash					300,000		300,000			100,000
Private Company Investments
Debt Securities, Available-for-sale [Line Items]
Other-than-temporary impairment loss					0	$ 0	0	$ 0
Significant Other Observable Inputs (Level 2)
Debt Securities, Available-for-sale [Line Items]
Real estate investments					0		0			0
Other investments					$ 895,000		$ 895,000			$ 2,079,000
1347 Investors LLC
Debt Securities, Available-for-sale [Line Items]
Ownership interest								26.70%
Subsequent Event
Debt Securities, Available-for-sale [Line Items]
(Gain) loss on change in fair value of limited liability investments, at fair value		$ (600,000)	$ (700,000)	$ (2,700,000)
Investment impairment losses		$ 700,000
Other than temporary impairment losses, investments, percent		90.00%