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		9 Months Ended	12 Months Ended
		Mar. 31, 2018		Dec. 31, 2018	Dec. 31, 2019		Dec. 31, 2018
Equity Investments [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Beginning balance		$ 9,521		$ 9,458	$ 9,197		$ 9,521
Gains (losses) included in earnings		(993)		(1,274)	87
Purchases, investments, and issuances		935		1,232	3,396
Sales, maturities, settlements, and distributions		(5)		(1,596)	(2,601)
Transfers in	[1]			1,377
Ending balance		9,458		9,197	10,079		9,197
Amounts related to held assets		(993)	[2]		$ (1,734)	[3]	(1,851)	[4]
Medallion Loans [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Beginning balance		208,279		161,155			208,279
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	[2]	(38,190)
Commercial Loans [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Beginning balance		90,188		93,620			90,188
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	[2]	(10)
Investment [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Beginning balance		302,147		331,169			302,147
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	[2]	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			7,450
Gains (losses) included in earnings		(1,915)
Ending balance		5,535
Amounts related to held assets	[2]	(1,915)
Other Assets [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Beginning balance		339		$ 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 March 31, 2018.

[3] Total realized and unrealized gains (losses) included in income for the period which relate to assets held as of December 31, 2019.

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