Stockholders' Equity - Net Income Attributable to Noncontrolling Interests (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Change In Ownership Interest [Line Items]
Net Income (Loss) Attributable To Noncontrolling Interests	$ 1,061	$ 2,466	$ 6,365	$ 5,323
Noncontrolling interests	65,090		65,090		69,789
Edgewater [Member]
Change In Ownership Interest [Line Items]
Net Income (Loss) Attributable To Noncontrolling Interests	1,060	2,018	5,732	4,671
Noncontrolling interests	64,360		64,360		66,641
LAZ-MD Holdings [Member]
Change In Ownership Interest [Line Items]
Net Income (Loss) Attributable To Noncontrolling Interests		365	631	862
Noncontrolling interests					2,566
Other [Member]
Change In Ownership Interest [Line Items]
Net Income (Loss) Attributable To Noncontrolling Interests	1	83	2	(210)
Noncontrolling interests	$ 730		$ 730		$ 582