Business Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2015 Segment Entity	Dec. 31, 2014 Entity	Dec. 31, 2013 Entity
Segment Reporting Disclosure [Line Items]
Number of business segments (segment)	1
Number of principal sources of revenue (source of revenue)	2
Advisory revenues as a percentage of total revenue	100.00%	102.00%	100.00%
Advisory revenues
Segment Reporting Disclosure [Line Items]
Number of clients that accounted for more than 10% of total revenues (entity) | Entity	0	0	1