Stockholders' Equity - Net Income Attributable to Noncontrolling Interests (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Change In Ownership Interest [Line Items]
Net Income (Loss) Attributable To Noncontrolling Interests	$ 4,587	$ 2,289
Noncontrolling interests	69,797		69,789
Edgewater [Member]
Change In Ownership Interest [Line Items]
Net Income (Loss) Attributable To Noncontrolling Interests	4,120	2,366
Noncontrolling interests	66,849		66,641
LAZ-MD Holdings [Member]
Change In Ownership Interest [Line Items]
Net Income (Loss) Attributable To Noncontrolling Interests	467	192
Noncontrolling interests	2,168		2,566
Other [Member]
Change In Ownership Interest [Line Items]
Net Income (Loss) Attributable To Noncontrolling Interests		(269)
Noncontrolling interests	$ 780		$ 582