Incentive Plans - Summary of Impact of Share-Based Incentive Plans on Compensation and Benefits Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share-based incentive awards:
Share-based incentive awards	$ 85,474	$ 60,687	$ 163,001	$ 155,325
RSUs [Member]
Share-based incentive awards:
Share-based incentive awards	54,354	40,564	110,295	94,972
PRSUs [Member]
Share-based incentive awards:
Share-based incentive awards	16,417	10,335	28,199	27,024
Restricted Stock [Member]
Share-based incentive awards:
Share-based incentive awards	13,161	8,342	22,810	31,818
DSUs [Member]
Share-based incentive awards:
Share-based incentive awards	$ 1,542	$ 1,446	$ 1,697	$ 1,511