Fair Value of Assets and Liabilities - Schedule of Changes in Fair Value of the Company's Level 3 Assets and Liabilities (Detail) - Fair Value, Measurements, Nonrecurring [Member] - USD ($) $ in Thousands		3 Months Ended					6 Months Ended		9 Months Ended
		Sep. 30, 2019		Sep. 30, 2018	Mar. 31, 2018		Sep. 30, 2018		Sep. 30, 2019
Equity Investments [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Beginning balance		$ 9,797		$ 10,773	$ 9,521		$ 9,458		$ 9,197
Gains (losses) included in earnings		414		(400)	(993)		(774)		510
Purchases, investments, and issuances		1,077		631	935		1,160		2,727
Sales, maturities, settlements, and distributions		(1,408)		(252)	(5)		(469)		(2,554)
Transfers in	[1]						1,377
Ending balance		9,880		10,752	9,458		10,752		9,880
Amounts related to held assets		$ (998)	[2]	$ (400)	(993)	[3]	(774)	[4]	$ (1,300)	[2]
Medallion Loans [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Beginning balance					208,279		161,155
Gains (losses) included in earnings					(38,190)
Purchases, investments, and issuances					7
Sales, maturities, settlements, and distributions					(8,941)
Ending balance					161,155
Amounts related to held assets	[3]				(38,190)
Commercial Loans [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Beginning balance					90,188		93,620
Gains (losses) included in earnings					(8)
Purchases, investments, and issuances					7,252
Sales, maturities, settlements, and distributions					(3,812)
Ending balance					93,620
Amounts related to held assets	[3]				(10)
Investment [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Beginning balance					302,147		331,169
Gains (losses) included in earnings					29,143
Purchases, investments, and issuances					462
Sales, maturities, settlements, and distributions					(583)
Ending balance					331,169
Amounts related to held assets	[3]				29,143
Investments Other than Securities [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Beginning balance					7,450		5,535
Gains (losses) included in earnings					(1,915)
Ending balance					5,535
Amounts related to held assets	[3]				(1,915)
Other Assets [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Beginning balance					339		$ 339
Ending balance					$ 339

[1] Represents the removal of RPAC investments eliminated in consolidation as well as the transfer of LAX from controlled subsidiaries during the 2018 second quarter.

[2] Total realized and unrealized gains (losses) included in income for the period which relate to assets held as of September 30, 2019.

[3] Total realized and unrealized gains (losses) included in income for the period, which relate to assets held as of March 31, 2018.

[4] Total realized and unrealized gains (losses) included in income for the period which relate to assets held as of September 30, 2018.