Goodwill and Other Intangible Assets, Net - Summary of Changes in Carrying Amount of Goodwill by Reportable Segment (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Goodwill And Intangible Assets [Line Items]
Beginning Balance	$ 164,874	$ 141,142
Acquisitions	1,296
Other	(1,776)
Cumulative translation adjustment	(1,055)	(901)
Ending Balance	163,339	164,874
Frederick Ross Acquisition [Member]
Goodwill And Intangible Assets [Line Items]
Acquisitions		8,489
Smith Mack Acquisition [Member]
Goodwill And Intangible Assets [Line Items]
Acquisitions		7,183
Grubb and Ellis Acquisition [Member]
Goodwill And Intangible Assets [Line Items]
Acquisitions		4,046
Goodwill Related to Newmark Affiliates [Member]
Goodwill And Intangible Assets [Line Items]
Acquisitions		611
Other Acquisitions [Member]
Goodwill And Intangible Assets [Line Items]
Acquisitions		4,304
Ending Balance		19,700
Financial Services [Member]
Goodwill And Intangible Assets [Line Items]
Beginning Balance	85,005	81,602
Acquisitions	1,296
Other	(83)
Cumulative translation adjustment	(1,055)	(901)
Ending Balance	85,163	85,005
Financial Services [Member] | Frederick Ross Acquisition [Member]
Goodwill And Intangible Assets [Line Items]
Acquisitions
Financial Services [Member] | Smith Mack Acquisition [Member]
Goodwill And Intangible Assets [Line Items]
Acquisitions
Financial Services [Member] | Grubb and Ellis Acquisition [Member]
Goodwill And Intangible Assets [Line Items]
Acquisitions
Financial Services [Member] | Goodwill Related to Newmark Affiliates [Member]
Goodwill And Intangible Assets [Line Items]
Acquisitions
Financial Services [Member] | Other Acquisitions [Member]
Goodwill And Intangible Assets [Line Items]
Acquisitions		4,304
Real Estate Services [Member]
Goodwill And Intangible Assets [Line Items]
Beginning Balance	79,869	59,540
Acquisitions
Other	(1,693)
Cumulative translation adjustment
Ending Balance	78,176	79,869
Real Estate Services [Member] | Frederick Ross Acquisition [Member]
Goodwill And Intangible Assets [Line Items]
Acquisitions		8,489
Real Estate Services [Member] | Smith Mack Acquisition [Member]
Goodwill And Intangible Assets [Line Items]
Acquisitions		7,183
Real Estate Services [Member] | Grubb and Ellis Acquisition [Member]
Goodwill And Intangible Assets [Line Items]
Acquisitions		4,046
Real Estate Services [Member] | Goodwill Related to Newmark Affiliates [Member]
Goodwill And Intangible Assets [Line Items]
Acquisitions		611
Real Estate Services [Member] | Other Acquisitions [Member]
Goodwill And Intangible Assets [Line Items]
Acquisitions
Ending Balance		$ 15,400