Significant Accounting Policies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Significant Accounting Policies [Line Items]
Foreign currency remeasurement gains (losses), net of hedge transactions	$ 131	$ (2,887)	$ (761)
Cash and cash equivalents maturity period	90 days or less
Short-term investments maturity days	Original maturities of 90 days or less
Depreciation and amortization expense	34,464	34,750	30,855
Change in goodwill impairment testing description	This change was preferable because it provides the Company with additional time to complete the annual goodwill impairment test in advance of its year-end reporting.
Annual date of goodwill impairment	Nov. 01, 2014	Nov. 01, 2013
Reimbursements of expenses	20,407	18,327	24,762
Soft dollar arrangement expenses	23,000
Operating Segments [Member] | Financial Advisory [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.
Days fee receivables are considered past due in excess	180 days
Depreciation and amortization expense	$ 4,826	$ 5,256	$ 5,710
Operating Segments [Member] | Asset Management [Member]
Significant Accounting Policies [Line Items]
Days fee receivables are considered past due in excess	12 months