Derivatives - Summary of Gains Losses on Derivative Contracts Included in Condensed Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Rate lock commitments | Compensation and employee benefits
Derivative Instruments, Gain (Loss)
Gain (loss) recognized in income for derivatives	$ 700	$ (200)	$ 1,600	$ 1,600
Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss)
Gain (loss) recognized in income for derivatives	5,788	(2,232)	4,780	(36,092)
Not Designated as Hedging Instrument | Nasdaq Forwards | Other income (loss), net
Derivative Instruments, Gain (Loss)
Gain (loss) recognized in income for derivatives	(5,771)	(8,214)	(7,543)	(37,181)
Not Designated as Hedging Instrument | Rate lock commitments | Gains from mortgage banking activities/originations, net
Derivative Instruments, Gain (Loss)
Gain (loss) recognized in income for derivatives	(3,951)	5,734	46,004	27,113
Not Designated as Hedging Instrument | Rate lock commitments | Compensation and employee benefits
Derivative Instruments, Gain (Loss)
Gain (loss) recognized in income for derivatives	(677)	236	(1,576)	(1,620)
Not Designated as Hedging Instrument | Forward sale contracts | Gains from mortgage banking activities/originations, net
Derivative Instruments, Gain (Loss)
Gain (loss) recognized in income for derivatives	$ 16,187	$ 12	$ (32,105)	$ (24,404)