BANK LOANS, NET, Held for Sale and Held for Investment (Details) $ in Thousands	Jun. 30, 2015 USD ($) segment	Sep. 30, 2014 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loan portfolio segments | segment	6
Loans Receivable Held-for-sale, Net [Abstract]
Loans receivable held-for-sale, net	$ 92,227	$ 45,988
Loans held for investment:
Total loans held for investment	12,155,612	11,103,418
Net unearned income and deferred expenses	(33,530)	(37,533)
Total loans held for investment, net	12,122,082	11,065,885
Total loans held for sale and investment	12,214,309	11,111,873
Allowance for loan losses	(160,631)	(147,574)
Bank loans, net	$ 12,053,678	$ 10,964,299
Associated percentage of each major loan category in loan portfolios [Abstract]
Loans held for sale, net (in hundredths)	1.00%	0.00%
Total loans held for sale and investment (in hundredths)	100.00%	100.00%
Domestic
Loans held for investment:
C&I loans	$ 5,609,932	$ 5,378,592
CRE construction loans	90,866	76,733
CRE loans	1,529,324	1,415,093
Tax-exempt loans	385,234	122,218
Residential mortgage loans	1,947,715	1,749,513
SBL	$ 1,389,227	$ 1,021,358
Associated percentage of each major loan category in loan portfolios [Abstract]
C&I loans (in hundredths)	46.00%	49.00%
CRE construction loans (in hundredths)	1.00%	1.00%
CRE loans (in hundredths)	12.00%	13.00%
Tax-exempt loans (in hundredths)	3.00%	1.00%
Residential mortgage loans (in hundredths)	16.00%	16.00%
SBL (in hundredths)	11.00%	9.00%
Foreign
Loans held for investment:
C&I loans	$ 929,710	$ 1,043,755
CRE construction loans	29,401	17,462
CRE loans	239,456	274,070
Residential mortgage loans	2,846	2,234
SBL	$ 1,901	$ 2,390
Associated percentage of each major loan category in loan portfolios [Abstract]
C&I loans (in hundredths)	8.00%	9.00%
CRE construction loans (in hundredths)	0.00%	0.00%
CRE loans (in hundredths)	2.00%	2.00%
Residential mortgage loans (in hundredths)	0.00%	0.00%
SBL (in hundredths)	0.00%	0.00%