Incentive Plans - Summary of Impact of Share-Based Incentive Plans on Compensation and Benefits Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based incentive awards:
Share-based incentive awards	$ 65,189	$ 48,357	$ 226,272	$ 218,187
RSUs [Member]
Share-based incentive awards:
Share-based incentive awards	37,206	38,121	140,597	154,643
PRSUs [Member]
Share-based incentive awards:
Share-based incentive awards	14,291	3,107	16,540	31,125
Restricted Stock [Member]
Share-based incentive awards:
Share-based incentive awards	7,274	6,950	24,871	30,323
Profits Interest Participation Rights [Member]
Share-based incentive awards:
Share-based incentive awards	6,224		42,105
DSUs [Member]
Share-based incentive awards:
Share-based incentive awards	$ 194	$ 179	$ 2,159	$ 2,096