BANK LOANS, NET, Credit Quality of Held for Investment Loan Portfolio (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Sep. 30, 2014
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	$ 12,166,788	$ 11,103,418
Performing residential first mortgage loans	1,730,941
LTV less than 50%
Financing Receivable, Recorded Investment [Line Items]
Performing residential first mortgage loans	557,456
LTV greater than 50% but less than 80%
Financing Receivable, Recorded Investment [Line Items]
Performing residential first mortgage loans	976,306
LTV greater than 80% but less than 100%
Financing Receivable, Recorded Investment [Line Items]
Performing residential first mortgage loans	169,304
LTV greater than 100% but less than 120%
Financing Receivable, Recorded Investment [Line Items]
Performing residential first mortgage loans	23,864
LTV greater than 120%
Financing Receivable, Recorded Investment [Line Items]
Performing residential first mortgage loans	4,011
C&I loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	6,813,200	6,422,347
CRE construction loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	100,914	94,195
CRE loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	1,672,945	1,689,163
Tax-exempt loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	361,644	122,218
First mortgage
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	1,945,723	1,731,763
Home equity
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	20,478	19,984
SBL and other consumer loan
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	1,251,884	1,023,748
Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	11,956,090	10,898,617
Pass | C&I loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	6,712,843	6,321,662
Pass | CRE construction loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	100,914	94,195
Pass | CRE loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	1,640,839	1,669,897
Pass | Tax-exempt loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	361,644	122,218
Pass | First mortgage
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	1,867,841	1,647,325
Pass | Home equity
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	20,125	19,572
Pass | SBL and other consumer loan
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	1,251,884	1,023,748
Special mention
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	100,615	98,638
Special mention | C&I loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	69,647	83,101
Special mention | CRE construction loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	0	0
Special mention | CRE loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	14,566	191
Special mention | Tax-exempt loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	0	0
Special mention | First mortgage
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	16,336	15,346
Special mention | Home equity
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	66	0
Special mention | SBL and other consumer loan
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	0	0
Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	110,083	105,255
Substandard | C&I loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	30,710	17,584
Substandard | CRE construction loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	0	0
Substandard | CRE loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	17,540	18,167
Substandard | Tax-exempt loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	0	0
Substandard | First mortgage
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	61,546	69,092
Substandard | Home equity
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	287	412
Substandard | SBL and other consumer loan
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment	0	0
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment		908
Doubtful | C&I loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment		0
Doubtful | CRE construction loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment		0
Doubtful | CRE loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment		908
Doubtful | Tax-exempt loans
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment		0
Doubtful | First mortgage
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment		0
Doubtful | Home equity
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment		0
Doubtful | SBL and other consumer loan
Financing Receivable, Recorded Investment [Line Items]
Total loans held for investment		$ 0