Unconsolidated Entities - Summary of Strategic Capital Revenues Recognized in Consolidated Statements of Income Related to Co-Investment Ventures (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Schedule Of Equity Method Investments [Line Items]
Total revenues	$ 621,276	$ 766,183	$ 1,314,932	$ 1,395,338
Unconsolidated Co-Investment Ventures [Member]
Schedule Of Equity Method Investments [Line Items]
Recurring fees	57,918	43,478	112,562	87,673
Transactional fees	11,828	12,626	27,452	21,219
Promote revenues	5,674	123,946	68,218	127,092
Total revenues	$ 75,420	$ 180,050	$ 208,232	$ 235,984