COMMITMENTS, CONTINGENCIES AND GUARANTEES (Details)						12 Months Ended									12 Months Ended									12 Months Ended
	Sep. 30, 2011 USD ($)		Sep. 30, 2010 USD ($)		Sep. 30, 2011 Loan commitments purchased from Allied Irish Bank [Member] USD ($)	Sep. 30, 2011 RJ Bank syndicated loans [Member] USD ($)	Sep. 30, 2011 Small business investment company commitment [Member] USD ($)	Sep. 30, 2011 Underwriting commitment [Member] CAD	Sep. 30, 2011 Deposits with clearing organizations [Member] USD ($)	Sep. 30, 2011 Loans to financial advisors and certain key revenue producers commitment [Member] USD ($)	Sep. 30, 2011 Independent venture capital or private equity partnerships commitment [Member] USD ($)	Sep. 30, 2011 Additional private equity limited partnerships commitment [Member] USD ($)	Sep. 30, 2011 Total independent venture capital, private equity partnerships, and private equity limited partnerships [Member] USD ($)	Sep. 30, 2011 Internally sponsored private equity limited partnership commitment [Member] USD ($)	Sep. 30, 2011 Commitment to lend to RJTCF [Member] USD ($)	Sep. 30, 2011 Lease agreements commitments [Member] USD ($)	Sep. 30, 2010 Lease agreements commitments [Member] USD ($)	Sep. 30, 2009 Lease agreements commitments [Member] USD ($)	Sep. 30, 2011 Interest rate swap guarantee [Member] USD ($)	Mar. 31, 2008 Line of credit guarantee [Member] USD ($)	Sep. 30, 2011 Mortgage debt guarantee [Member] USD ($)	Sep. 30, 2011 Project partnerships sold guarantee [Member] USD ($)	Sep. 30, 2011 Performance to third parties on certain obligations guarantee [Member] USD ($)	Sep. 30, 2011 Delivery of certain tax credits and other tax benefits guarantee [Member] USD ($)	Sep. 30, 2011 ARS Matters [Member] USD ($)	Sep. 30, 2011 Legal matter contingencies [Member] USD ($)
Commitments and contingencies [Abstract]
Amount of commitment					$ 615,000,000		$ 2,000,000	900,000		$ 20,900,000	$ 65,300,000	$ 38,200,000		$ 6,500,000	$ 150,000,000
Amount of commitments outstanding					500,000,000
Amount of purchased syndicated loans not yet settled						72,700,000
Settlement of purchased syndicated loans (in days)						90D
Amount of commitment fulfilled							800,000						70,000,000	6,500,000
Value of margin securities pledged									108,000,000
Amount of deposit required with clearing organization									78,500,000
Amount of commitment, minimum increment											200,000
Amount of commitment, maximum increment											5,000,000
Number of different independent venture capital or private equity partnerships											47
Number of additional private equity limited partnerships												2
Amount of invested distributions received													47,800,000	5,200,000
Number of internally sponsored private equity limited partnership														1
Number of days that investments in project partnerships are typically sold (in days)															90D
Cash funded to invest in loans or investments in project partnerships															38,800,000
Minimum annual rental payments, due in 2012																46,000,000
Minimum annual rental payments, due in 2013																41,800,000
Minimum annual rental payments, due in 2014																33,500,000
Minimum annual rental payments, due in 2015																27,300,000
Minimum annual rental payments, due in 2016																23,700,000
Minimum annual rental payments, due after 2016																57,400,000
Rental expense incurred under leases																56,200,000	55,200,000	55,200,000
Approximate market values of collateral received that can be repledged [Abstract]
Securities purchased under agreements to resell and other collateralized financings	397,739,000
Securities received in securities borrowed vs. cash transactions	212,015,000
Collateral received for margin loans	1,248,290,000
Total	1,858,044,000
Approximate market values of collateral repledged and financial instruments that we own and pledged [Abstract]
Securities sold under agreements to repurchase	206,474,000
Securities delivered in securities loaned vs. cash transactions	771,130,000
Collateral used for cash loans	15,000
Collateral used for deposits at clearing organizations	119,387,000
Total	1,097,006,000
Guarantees [Abstract]
Current exposure of guarantees																			14,800,000	8,000,000	52,800,000	1,700,000	39,700,000	57,000,000
Estimated total potential exposure of guarantee																			18,100,000			1,700,000	39,700,000	57,000,000
Number of funds offering guaranteed performance to various third-parties on certain obligations																							1
Number of years under the guarantee to deliver a certain amount of tax credits and other tax benefits (in years)																								10Y
Low-Income Housing Tax Credit Fund Financing Asset	41,629,000	[1]	43,398,000	[1]																				41,600,000
Amount of liability related to the Low-Income Housing Tax Credit Fund Financing Asset	41,700,000		43,400,000																					41,700,000
ARS matters [Abstract]
Period over which offer to purchase ARS at par remained open (in days)																									75D
Par value of ARS repurchased																									245,000,000
Repurchased ARS redeemed at par																									15,900,000
Fair value of ARS repurchased																									205,000,000
Excess of par over fair value of ARS repurchased																									40,000,000
Make-whole payment to eligible clients for losses incurred on ARS purchased																									1,000,000
Legal matter contingencies [Abstract]
Estimate of range of possible loss, minimum																										0
Estimate of range of possible loss, maximum, in excess of accrued liability (if any)																										$ 10,000,000

[1] In fiscal year 2010 we sold an investment in a low-income housing tax credit fund and we provided a guaranteed return on investment to the purchaser. As a result of this guarantee obligation, we are the primary beneficiary of the fund (see Note 9 for further information regarding the consolidation of this fund) and we have accounted for this transaction as a financing. As a financing transaction, we continue to account for the asset transferred to the purchaser, and maintain a related liability corresponding to our obligations under the guarantee. As the benefits are delivered to the purchaser of the investment, this financing asset and the related liability will decrease. The related financing liability in the amount of $41.7 million and $43.4 million is included in Trade and Other Payables on our Consolidated Statements of Financial Condition as of September 30, 2011 and 2010, respectively. See Note 17 for further discussion of our obligations under the guarantee.