Derivatives - Summary of Gains Losses on Derivative Contracts Included in Condensed Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Rate lock commitments | Compensation and employee benefits
Derivative Instruments, Gain (Loss)
Gain (loss) recognized in income for derivatives	$ 2,100	$ 2,000	$ 1,700
Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss)
Gain (loss) recognized in income for derivatives	(2,962)	(30,354)	17,233
Not Designated as Hedging Instrument | Nasdaq Forwards | Other income (loss), net
Derivative Instruments, Gain (Loss)
Gain (loss) recognized in income for derivatives	(13,680)	(51,117)	19,002
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	20,125	21,916	935
Not Designated as Hedging Instrument | Rate lock commitments | Compensation and employee benefits
Derivative Instruments, Gain (Loss)
Gain (loss) recognized in income for derivatives	(2,068)	(2,004)	(1,673)
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	$ (7,339)	$ 851	$ (1,031)