Revenues from Contracts with Customers - Schedule of Revenues from Contracts with Customers and Our Other Sources of Revenues (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 1,842,402	$ 1,700,786
Gains from mortgage banking activities/originations, net	198,085	182,264	$ 206,000
Servicing fees and other	177,645	164,529
Revenues	2,218,132	2,047,579	1,596,450
Leasing and other commissions
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	854,780	817,435
Revenues	854,780	817,435	616,980
Capital markets commissions
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	541,255	468,904
Revenues	541,255	468,904	$ 397,736
Management services
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 446,367	$ 414,447