FAIR VALUE, Recurring and Nonrecurring Fair Value Measurements (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Assets, Fair Value Disclosure [Abstract]
Total debt securities	$ 581,837	$ 602,973
Derivative contracts	42,086	28,205
Equity securities	28,344	34,142
Corporate loans	4,814	990
Other	33,470	13,083
Total trading instruments	690,551	679,393
Available for sale securities	513,730	562,289	$ 698,844
Derivative instruments associated with offsetting matched book positions	389,457	323,337
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	262,162	215,142
Derivative liability	20,239	12,372
Equity securities	3,098	10,886
Other securities	2,494	0
Total trading instruments sold but not yet purchased	287,993	238,400
Derivative instruments associated with offsetting matched book positions, at fair value	389,457	323,337
Transfers of Financial Instruments into (out of) Level 1 and 2 [Abstract]
Fair Value of Financial Instruments, Level 1 to Level 2 Transfers	1,100	800
Fair Value of Financial Instruments, Level 2 to Level 1 Transfers	1,800	1,300
Adjustments to fair value of nonrecurring fair value measurements [Abstract]
Additional provision for loan losses due to fair value adjustment	900	500
Other losses due to fair value adjustment	300	200
Recurring
Assets, Fair Value Disclosure [Abstract]
Total debt securities	581,837	602,973
Netting adjustments	(90,621)	(61,718)
Equity securities	28,344	34,142
Corporate loans	4,814	990
Other	33,470	13,083
Total trading instruments	690,551	679,393
Available for sale securities	513,730	562,289
Private equity investments	209,088	211,666
Other investments	248,751	215,751
Derivative instruments associated with offsetting matched book positions	389,457
Deposits with clearing organizations	29,701
Total other assets	5,892
Total assets at fair value on a recurring basis	2,087,170	1,995,685
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	262,162	215,142
Netting adjustments	(88,881)	(63,296)
Equity securities	3,098	10,886
Other securities	2,494
Total trading instruments sold but not yet purchased	287,993	238,400
Derivative instruments associated with offsetting matched book positions, at fair value	389,457	323,337
Other liabilities		58
Total liabilities at fair value on a recurring basis	685,053	561,795
Adjustments to fair value of nonrecurring fair value measurements [Abstract]
Other investments with obligations to perform under deferred compensation plan	106,000	144,000
Recurring | Municipal and provincial obligations
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	18,313	11,647
Recurring | Corporate obligations
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	33,184	15,333
Recurring | Government obligations
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	205,658	187,424
Recurring | Agency MBS and CMOs
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	5,007	738
Recurring | Trade and other payables
Liabilities, Fair Value Disclosure [Abstract]
Other liabilities	58
Total trade and other payables	7,603
Recurring | Municipal and provincial obligations
Assets, Fair Value Disclosure [Abstract]
Total debt securities	206,063	203,889
Recurring | Corporate obligations
Assets, Fair Value Disclosure [Abstract]
Total debt securities	95,317	111,928
Recurring | Government and agency obligations
Assets, Fair Value Disclosure [Abstract]
Total debt securities	115,947	101,362
Recurring | Agency MBS and CMOs
Assets, Fair Value Disclosure [Abstract]
Total debt securities	117,570	127,419
Available for sale securities	302,195	267,720
Recurring | Non-agency CMOs and ABS
Assets, Fair Value Disclosure [Abstract]
Total debt securities	46,940	58,375
Recurring | Non-agency CMOs
Assets, Fair Value Disclosure [Abstract]
Available for sale securities	71,369	91,918
Recurring | Other securities
Assets, Fair Value Disclosure [Abstract]
Available for sale securities	1,402	1,916
Recurring | ARS – municipals
Assets, Fair Value Disclosure [Abstract]
Available for sale securities	28,015	86,696
Recurring | ARS - preferred securities
Assets, Fair Value Disclosure [Abstract]
Available for sale securities	110,749	114,039
Recurring | Other assets
Assets, Fair Value Disclosure [Abstract]
Other assets	4,975	787
Total other assets		3,249
Recurring | Quoted prices in active markets for identical assets (Level 1)
Assets, Fair Value Disclosure [Abstract]
Total debt securities	27,606	21,019
Equity securities	24,859	28,834
Corporate loans	0	0
Other	679	566
Total trading instruments	53,144	50,419
Available for sale securities	1,402	1,916
Private equity investments	0	0
Other investments	230,839	212,753
Derivative instruments associated with offsetting matched book positions	0
Deposits with clearing organizations	29,701
Total assets at fair value on a recurring basis	315,086	265,088
Bank loans, net	0	0
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	228,798	199,284
Equity securities	3,098	10,884
Other securities	0
Total trading instruments sold but not yet purchased	231,896	210,168
Derivative instruments associated with offsetting matched book positions, at fair value	0	0
Other liabilities		0
Total liabilities at fair value on a recurring basis	231,896	210,168
Recurring | Quoted prices in active markets for identical assets (Level 1) | Municipal and provincial obligations
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	17,966	11,093
Recurring | Quoted prices in active markets for identical assets (Level 1) | Corporate obligations
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	167	29
Recurring | Quoted prices in active markets for identical assets (Level 1) | Government obligations
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	205,658	187,424
Recurring | Quoted prices in active markets for identical assets (Level 1) | Agency MBS and CMOs
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	5,007	738
Recurring | Quoted prices in active markets for identical assets (Level 1) | Trade and other payables
Liabilities, Fair Value Disclosure [Abstract]
Other liabilities	0
Total trade and other payables	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | Municipal and provincial obligations
Assets, Fair Value Disclosure [Abstract]
Total debt securities	17,318	11,407
Recurring | Quoted prices in active markets for identical assets (Level 1) | Corporate obligations
Assets, Fair Value Disclosure [Abstract]
Total debt securities	2,254	1,989
Recurring | Quoted prices in active markets for identical assets (Level 1) | Government and agency obligations
Assets, Fair Value Disclosure [Abstract]
Total debt securities	7,781	7,376
Recurring | Quoted prices in active markets for identical assets (Level 1) | Agency MBS and CMOs
Assets, Fair Value Disclosure [Abstract]
Total debt securities	253	247
Available for sale securities	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | Non-agency CMOs and ABS
Assets, Fair Value Disclosure [Abstract]
Total debt securities	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | Non-agency CMOs
Assets, Fair Value Disclosure [Abstract]
Available for sale securities	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | Other securities
Assets, Fair Value Disclosure [Abstract]
Available for sale securities	1,402	1,916
Recurring | Quoted prices in active markets for identical assets (Level 1) | ARS – municipals
Assets, Fair Value Disclosure [Abstract]
Available for sale securities	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | ARS - preferred securities
Assets, Fair Value Disclosure [Abstract]
Available for sale securities	0	0
Recurring | Quoted prices in active markets for identical assets (Level 1) | Other assets
Assets, Fair Value Disclosure [Abstract]
Other assets	0	0
Total other assets	0	0
Recurring | Significant other observable inputs (Level 2)
Assets, Fair Value Disclosure [Abstract]
Total debt securities	554,066	581,943
Equity securities	3,485	5,264
Corporate loans	4,814	990
Other	30,805	10,208
Total trading instruments	725,877	688,328
Available for sale securities	373,564	359,638
Private equity investments	0	0
Other investments	17,347	1,267
Derivative instruments associated with offsetting matched book positions	389,457
Deposits with clearing organizations	0
Total other assets	917
Total assets at fair value on a recurring basis	1,507,162	1,375,032
Bank loans, net	105,199	23,678
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	33,364	15,858
Equity securities	0	2
Other securities	2,494
Total trading instruments sold but not yet purchased	144,978	91,528
Derivative instruments associated with offsetting matched book positions, at fair value	389,457	323,337
Other liabilities		0
Total liabilities at fair value on a recurring basis	541,980	414,865
Recurring | Significant other observable inputs (Level 2) | Municipal and provincial obligations
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	347	554
Recurring | Significant other observable inputs (Level 2) | Corporate obligations
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	33,017	15,304
Recurring | Significant other observable inputs (Level 2) | Government obligations
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	0	0
Recurring | Significant other observable inputs (Level 2) | Agency MBS and CMOs
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	0	0
Recurring | Significant other observable inputs (Level 2) | Trade and other payables
Liabilities, Fair Value Disclosure [Abstract]
Other liabilities	0
Total trade and other payables	7,545
Recurring | Significant other observable inputs (Level 2) | Municipal and provincial obligations
Assets, Fair Value Disclosure [Abstract]
Total debt securities	188,745	192,482
Recurring | Significant other observable inputs (Level 2) | Corporate obligations
Assets, Fair Value Disclosure [Abstract]
Total debt securities	92,907	109,939
Recurring | Significant other observable inputs (Level 2) | Government and agency obligations
Assets, Fair Value Disclosure [Abstract]
Total debt securities	108,166	93,986
Recurring | Significant other observable inputs (Level 2) | Agency MBS and CMOs
Assets, Fair Value Disclosure [Abstract]
Total debt securities	117,317	127,172
Available for sale securities	302,195	267,720
Recurring | Significant other observable inputs (Level 2) | Non-agency CMOs and ABS
Assets, Fair Value Disclosure [Abstract]
Total debt securities	46,931	58,364
Recurring | Significant other observable inputs (Level 2) | Non-agency CMOs
Assets, Fair Value Disclosure [Abstract]
Available for sale securities	71,369	91,918
Recurring | Significant other observable inputs (Level 2) | Other securities
Assets, Fair Value Disclosure [Abstract]
Available for sale securities	0	0
Recurring | Significant other observable inputs (Level 2) | ARS – municipals
Assets, Fair Value Disclosure [Abstract]
Available for sale securities	0	0
Recurring | Significant other observable inputs (Level 2) | ARS - preferred securities
Assets, Fair Value Disclosure [Abstract]
Available for sale securities	0	0
Recurring | Significant other observable inputs (Level 2) | Other assets
Assets, Fair Value Disclosure [Abstract]
Other assets	0	0
Total other assets		2,462
Recurring | Significant unobservable inputs (Level 3)
Assets, Fair Value Disclosure [Abstract]
Total debt securities	165	11
Equity securities	0	44
Corporate loans	0	0
Other	1,986	2,309
Total trading instruments	2,151	2,364
Available for sale securities	138,764	200,735
Private equity investments	209,088	211,666
Other investments	565	1,731
Derivative instruments associated with offsetting matched book positions	0
Deposits with clearing organizations	0
Total other assets	4,975
Total assets at fair value on a recurring basis	355,543	417,283
Bank loans, net	12,799,065	10,738,136
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	0	0
Equity securities	0	0
Other securities	0
Total trading instruments sold but not yet purchased	0	0
Derivative instruments associated with offsetting matched book positions, at fair value	0	0
Other liabilities		58
Total liabilities at fair value on a recurring basis	58	58
Auction rate securities [Abstract]
Jefferson County, Alabama limited obligation school warrants ARS, fair value disclosure		58,000
Private Equity Investments [Abstract]
Portion of significant private equity investments included in Noncontrolling Interests	52,000	55,000
Portion of private equity investments owned by parent	$ 157,000	$ 157,000
Weighted-average ownership percentage (in hundredths)	75.00%	74.00%
Recurring | Significant unobservable inputs (Level 3) | Municipal and provincial obligations
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	$ 0	$ 0
Recurring | Significant unobservable inputs (Level 3) | Corporate obligations
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	0	0
Recurring | Significant unobservable inputs (Level 3) | Government obligations
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	0	0
Recurring | Significant unobservable inputs (Level 3) | Agency MBS and CMOs
Liabilities, Fair Value Disclosure [Abstract]
Total debt securities	0	0
Recurring | Significant unobservable inputs (Level 3) | Trade and other payables
Liabilities, Fair Value Disclosure [Abstract]
Other liabilities	58
Total trade and other payables	58
Recurring | Significant unobservable inputs (Level 3) | Municipal and provincial obligations
Assets, Fair Value Disclosure [Abstract]
Total debt securities	0	0
Recurring | Significant unobservable inputs (Level 3) | Corporate obligations
Assets, Fair Value Disclosure [Abstract]
Total debt securities	156	0
Recurring | Significant unobservable inputs (Level 3) | Government and agency obligations
Assets, Fair Value Disclosure [Abstract]
Total debt securities	0	0
Recurring | Significant unobservable inputs (Level 3) | Agency MBS and CMOs
Assets, Fair Value Disclosure [Abstract]
Total debt securities	0	0
Available for sale securities	0	0
Recurring | Significant unobservable inputs (Level 3) | Non-agency CMOs and ABS
Assets, Fair Value Disclosure [Abstract]
Total debt securities	9	11
Recurring | Significant unobservable inputs (Level 3) | Non-agency CMOs
Assets, Fair Value Disclosure [Abstract]
Available for sale securities	0	0
Recurring | Significant unobservable inputs (Level 3) | Other securities
Assets, Fair Value Disclosure [Abstract]
Available for sale securities	0	0
Recurring | Significant unobservable inputs (Level 3) | ARS – municipals
Assets, Fair Value Disclosure [Abstract]
Available for sale securities	28,015	86,696
Recurring | Significant unobservable inputs (Level 3) | ARS - preferred securities
Assets, Fair Value Disclosure [Abstract]
Available for sale securities	110,749	114,039
Recurring | Significant unobservable inputs (Level 3) | Other assets
Assets, Fair Value Disclosure [Abstract]
Netting adjustments		0
Other assets	4,975	787
Total other assets		787
Nonrecurring
Assets, Fair Value Disclosure [Abstract]
Bank loans, net	80,246	112,938
OREO	671	768
Total assets at fair value on a nonrecurring basis	80,917	113,706
Nonrecurring | Impaired loans
Assets, Fair Value Disclosure [Abstract]
Bank loans, net	65,912	90,327
Nonrecurring | Loans held for sale
Assets, Fair Value Disclosure [Abstract]
Bank loans, net	14,334	22,611
Nonrecurring | Quoted prices in active markets for identical assets (Level 1)
Assets, Fair Value Disclosure [Abstract]
Bank loans, net	0	0
OREO	0	0
Total assets at fair value on a nonrecurring basis	0	0
Nonrecurring | Quoted prices in active markets for identical assets (Level 1) | Impaired loans
Assets, Fair Value Disclosure [Abstract]
Bank loans, net	0	0
Nonrecurring | Quoted prices in active markets for identical assets (Level 1) | Loans held for sale
Assets, Fair Value Disclosure [Abstract]
Bank loans, net	0	0
Nonrecurring | Significant other observable inputs (Level 2)
Assets, Fair Value Disclosure [Abstract]
Bank loans, net	42,416	57,410
OREO	671	768
Total assets at fair value on a nonrecurring basis	43,087	58,178
Nonrecurring | Significant other observable inputs (Level 2) | Impaired loans
Assets, Fair Value Disclosure [Abstract]
Bank loans, net	28,082	34,799
Nonrecurring | Significant other observable inputs (Level 2) | Loans held for sale
Assets, Fair Value Disclosure [Abstract]
Bank loans, net	14,334	22,611
Nonrecurring | Significant unobservable inputs (Level 3)
Assets, Fair Value Disclosure [Abstract]
Bank loans, net	37,830	55,528
OREO	0	0
Total assets at fair value on a nonrecurring basis	37,830	55,528
Nonrecurring | Significant unobservable inputs (Level 3) | Impaired loans
Assets, Fair Value Disclosure [Abstract]
Bank loans, net	37,830	55,528
Nonrecurring | Significant unobservable inputs (Level 3) | Loans held for sale
Assets, Fair Value Disclosure [Abstract]
Bank loans, net	0	0
Interest rate contract | Recurring
Assets, Fair Value Disclosure [Abstract]
Netting adjustments	(90,621)	(61,718)
Derivative contracts	42,086	28,205
Derivative instruments associated with offsetting matched book positions		323,337
Liabilities, Fair Value Disclosure [Abstract]
Netting adjustments	(88,881)	(63,296)
Derivative liability	20,239	12,372
Interest rate contract | Recurring | Trade and other payables
Liabilities, Fair Value Disclosure [Abstract]
Derivative liability	7,545
Interest rate contract | Recurring | Other assets
Assets, Fair Value Disclosure [Abstract]
Derivative contracts		2,462
Interest rate contract | Recurring | Quoted prices in active markets for identical assets (Level 1)
Assets, Fair Value Disclosure [Abstract]
Derivative contracts asset, gross	0	0
Derivative instruments associated with offsetting matched book positions		0
Liabilities, Fair Value Disclosure [Abstract]
Derivative contracts liability, gross	0	0
Interest rate contract | Recurring | Quoted prices in active markets for identical assets (Level 1) | Trade and other payables
Liabilities, Fair Value Disclosure [Abstract]
Derivative contracts liability, gross	0
Interest rate contract | Recurring | Quoted prices in active markets for identical assets (Level 1) | Other assets
Assets, Fair Value Disclosure [Abstract]
Derivative contracts asset, gross		0
Interest rate contract | Recurring | Significant other observable inputs (Level 2)
Assets, Fair Value Disclosure [Abstract]
Derivative contracts asset, gross	132,707	89,923
Derivative instruments associated with offsetting matched book positions		323,337
Liabilities, Fair Value Disclosure [Abstract]
Derivative contracts liability, gross	109,120	75,668
Interest rate contract | Recurring | Significant other observable inputs (Level 2) | Trade and other payables
Liabilities, Fair Value Disclosure [Abstract]
Derivative contracts liability, gross	7,545
Interest rate contract | Recurring | Significant other observable inputs (Level 2) | Other assets
Assets, Fair Value Disclosure [Abstract]
Derivative contracts asset, gross		2,462
Interest rate contract | Recurring | Significant unobservable inputs (Level 3)
Assets, Fair Value Disclosure [Abstract]
Derivative contracts asset, gross	0	0
Derivative instruments associated with offsetting matched book positions		0
Liabilities, Fair Value Disclosure [Abstract]
Derivative contracts liability, gross	0	0
Interest rate contract | Recurring | Significant unobservable inputs (Level 3) | Trade and other payables
Liabilities, Fair Value Disclosure [Abstract]
Derivative contracts liability, gross	0
Interest rate contract | Recurring | Significant unobservable inputs (Level 3) | Other assets
Assets, Fair Value Disclosure [Abstract]
Derivative contracts asset, gross		$ 0
Forward foreign exchange contracts | Recurring
Assets, Fair Value Disclosure [Abstract]
Netting adjustments	0
Derivative contracts	917
Forward foreign exchange contracts | Recurring | Quoted prices in active markets for identical assets (Level 1)
Assets, Fair Value Disclosure [Abstract]
Derivative contracts asset, gross	0
Forward foreign exchange contracts | Recurring | Significant other observable inputs (Level 2)
Assets, Fair Value Disclosure [Abstract]
Derivative contracts asset, gross	917
Forward foreign exchange contracts | Recurring | Significant unobservable inputs (Level 3)
Assets, Fair Value Disclosure [Abstract]
Derivative contracts asset, gross	$ 0