Stockholders' Equity - Net Income Attributable to Noncontrolling Interests (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Change In Ownership Interest [Line Items]
Net Income (Loss) Attributable To Noncontrolling Interests	$ (421)	$ 2,466	$ 568	$ 2,289	$ 1,259	$ 372	$ 3,341	$ 3,504	$ 4,902	$ 8,476	$ 15,642
Noncontrolling interests	69,789				81,884				69,789	81,884
Edgewater [Member]
Change In Ownership Interest [Line Items]
Net Income (Loss) Attributable To Noncontrolling Interests									3,913	3,491	4,130
Noncontrolling interests	66,641				75,262				66,641	75,262
LAZ-MD Holdings [Member]
Change In Ownership Interest [Line Items]
Net Income (Loss) Attributable To Noncontrolling Interests									1,198	5,114	11,964
Noncontrolling interests	2,566				5,405				2,566	5,405
Other [Member]
Change In Ownership Interest [Line Items]
Net Income (Loss) Attributable To Noncontrolling Interests									(209)	(129)	(452)
Noncontrolling interests	$ 582				$ 1,217				$ 582	$ 1,217