CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 96,891	$ 198,682
Noncash items included in net income:
Depreciation and amortization of property	22,472	18,176
Amortization of deferred expenses, share-based incentive compensation and interest rate hedge	252,812	228,213
Amortization of intangible assets related to acquisitions	6,172	4,896
Gain on extinguishment of debt		(18,171)
(Increase) decrease in operating assets:
Deposits with banks	18,465	96,193
Cash deposited with clearing organizations and other segregated cash	13,614	28,574
Receivables-net	23,115	(28,681)
Investments	(55,135)	71,127
Other assets	(54,449)	(64,267)
Increase (decrease) in operating liabilities:
Deposits and other payables	(28,361)	(22,187)
Accrued compensation and benefits and other liabilities	(55,770)	(230,935)
Net cash provided by operating activities	239,826	281,620
CASH FLOWS FROM INVESTING ACTIVITIES:
Additions to property	(71,722)	(17,277)
Disposals of property	2,158	353
Net cash used in investing activities	(69,564)	(16,924)
Proceeds from:
Contribution from noncontrolling interests	1,544	3,821
Excess tax benefits from share-based incentive compensation		2,848
Payments for:
Subordinated debt		(131,829)
Capital lease obligations	(1,878)	(1,600)
Distributions to noncontrolling interests	(17,399)	(21,431)
Repurchase of common membership interests from members of LAZ-MD Holdings		(794)
Purchase of Class A common stock	(222,679)	(158,617)
Class A common stock dividends	(66,219)	(51,409)
Settlement of vested share-based incentive compensation	(40,686)	(92,337)
Other financing activities	(99)	(33,386)
Net cash used in financing activities	(347,416)	(484,734)
EFFECT OF EXCHANGE RATE CHANGES ON CASH	6,303	237
NET DECREASE IN CASH AND CASH EQUIVALENTS	(170,851)	(219,801)
CASH AND CASH EQUIVALENTS-January 1	1,003,791	1,209,695
CASH AND CASH EQUIVALENTS-September 30	832,940	989,894
Supplemental investing non-cash transaction:
Class A common stock issued/issuable in connection with business acquisitions		$ 39,654