Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Significant Accounting Policies [Line Items]
Foreign currency remeasurement gains (losses), net of hedge transactions	$ (1,153,000)	$ 1,589,000	$ 131,000
Depreciation and amortization expense	$ 33,264,000	32,785,000	34,464,000
Annual date of goodwill impairment	Nov. 01, 2016
Goodwill impairment loss	$ 0	0	0
Recoverable expenses	16,998,000	19,358,000	20,407,000
Soft dollar arrangement expenses	$ 23,000,000
Operating Segments [Member] | Financial Advisory Segment [Member]
Significant Accounting Policies [Line Items]
Fees receivable outstanding past due	60 days
Contractual payment term description relating to our interest-bearing financing receivables	Financial Advisory transactions include specific contractual payment terms that may vary from one month to four years following the invoice date or may be subject to court approval.
Period receivables past due in excess of 180 days are fully provided unless there is evidence that the balance is collectible	180 days
Depreciation and amortization expense	$ 5,661,000	4,412,000	4,826,000
Operating Segments [Member] | Asset Management Segment [Member]
Significant Accounting Policies [Line Items]
Fees receivable outstanding past due	12 months
Depreciation and amortization expense	$ 3,666,000	$ 2,957,000	$ 2,610,000