BANK LOANS, NET, Analysis of Payment Status of Loans Held for Investment (Details) (USD $)	3 Months Ended		6 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014	Sep. 30, 2014
Analysis of payment status of loans held for investment [Abstract]
30-89 days and accruing	$ 2,998,000		$ 2,998,000		$ 1,829,000
90 days or more and accruing	0		0		0
Total past due and accruing	2,998,000		2,998,000		1,829,000
Nonaccrual	69,638,000		69,638,000		80,665,000
Current and accruing	12,094,152,000		12,094,152,000		11,020,924,000
Total loans held for investment	12,166,788,000		12,166,788,000		11,103,418,000
Performing nonaccrual loans	36,900,000		36,900,000		41,400,000
Impaired interest lost on nonaccrual loans	487,000	1,000,000	1,200,000	1,800,000
Impaired financing receivable, interest income recognized	417,000	326,000	645,000	888,000
Other real estate owned fair value	6,500,000		6,500,000		5,400,000
C&I loans
Analysis of payment status of loans held for investment [Abstract]
30-89 days and accruing	173,000		173,000		124,000
90 days or more and accruing	0		0		0
Total past due and accruing	173,000		173,000		124,000
Nonaccrual	0		0		0
Current and accruing	6,813,027,000		6,813,027,000		6,422,223,000
Total loans held for investment	6,813,200,000		6,813,200,000		6,422,347,000
CRE construction loans
Analysis of payment status of loans held for investment [Abstract]
30-89 days and accruing	0		0		0
90 days or more and accruing	0		0		0
Total past due and accruing	0		0		0
Nonaccrual	0		0		0
Current and accruing	100,914,000		100,914,000		94,195,000
Total loans held for investment	100,914,000		100,914,000		94,195,000
CRE loans
Analysis of payment status of loans held for investment [Abstract]
30-89 days and accruing	0		0		0
90 days or more and accruing	0		0		0
Total past due and accruing	0		0		0
Nonaccrual	17,171,000		17,171,000		18,876,000
Current and accruing	1,655,774,000		1,655,774,000		1,670,287,000
Total loans held for investment	1,672,945,000		1,672,945,000		1,689,163,000
Tax-exempt loans
Analysis of payment status of loans held for investment [Abstract]
30-89 days and accruing	0		0		0
90 days or more and accruing	0		0		0
Total past due and accruing	0		0		0
Nonaccrual	0		0		0
Current and accruing	361,644,000		361,644,000		122,218,000
Total loans held for investment	361,644,000		361,644,000		122,218,000
Residential mortgage - first mortgage loans
Analysis of payment status of loans held for investment [Abstract]
30-89 days and accruing	2,795,000		2,795,000		1,648,000
90 days or more and accruing	0		0		0
Total past due and accruing	2,795,000		2,795,000		1,648,000
Nonaccrual	52,182,000		52,182,000		61,391,000
Current and accruing	1,890,746,000		1,890,746,000		1,668,724,000
Total loans held for investment	1,945,723,000		1,945,723,000		1,731,763,000
Residential mortgage - home equity loans/lines
Analysis of payment status of loans held for investment [Abstract]
30-89 days and accruing	30,000		30,000		57,000
90 days or more and accruing	0		0		0
Total past due and accruing	30,000		30,000		57,000
Nonaccrual	285,000		285,000		398,000
Current and accruing	20,163,000		20,163,000		19,529,000
Total loans held for investment	20,478,000		20,478,000		19,984,000
SBL
Analysis of payment status of loans held for investment [Abstract]
30-89 days and accruing	0		0		0
90 days or more and accruing	0		0		0
Total past due and accruing	0		0		0
Nonaccrual	0		0		0
Current and accruing	1,251,884,000		1,251,884,000		1,023,748,000
Total loans held for investment	$ 1,251,884,000		$ 1,251,884,000		$ 1,023,748,000