Derivatives - Summary of Gains Losses on Derivative Contracts Included in Condensed Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Rate lock commitments | Compensation and employee benefits
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in income for derivatives	$ 2,000	$ 1,700	$ 1,400
Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in income for derivatives	(30,354)	17,233	3,629
Not Designated as Hedging Instrument | Nasdaq Forwards | Other income (loss), net
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in income for derivatives	(51,117)	19,002	0
Not Designated as Hedging Instrument | Rate lock commitments | Gains from mortgage banking activities/originations, net
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in income for derivatives	21,916	935	1,953
Not Designated as Hedging Instrument | Rate lock commitments | Compensation and employee benefits
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in income for derivatives	(2,004)	(1,673)	(1,420)
Not Designated as Hedging Instrument | Forward Sale Contracts | Gains from mortgage banking activities/originations, net
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in income for derivatives	$ 851	$ (1,031)	$ 3,096