BANK LOANS, NET, Allowance for Loan Losses (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended
	Jun. 30, 2011		Jun. 30, 2010	Jun. 30, 2011		Jun. 30, 2010	Sep. 30, 2010
Changes in the allowance for loan losses [Roll Forward]
Balance at beginning of period	$ 146,115			$ 147,084
Provision for loan losses	8,363		17,098	28,232		59,870
Net charge-offs:
Charge-offs	(9,910)			(32,067)
Recoveries	1,232			2,551
Net charge-offs	(8,678)			(29,516)
Balance at end of period	145,800			145,800
Net charge-offs to average bank loans outstanding (annualized) (in hundredths)	0.55%			0.63%
Allowance for loan losses:
Individually evaluated for impairment	15,912			15,912			11,281
Collectively evaluated for impairment	129,888			129,888			135,803
Total allowance for loan losses	145,800			145,800
Loan category as a % of total recorded investment	100.00%			100.00%			100.00%
Recorded investment:
Individually evaluated for impairment	72,459	[1]		72,459	[1]		83,201	[1]
Collectively evaluated for impairment	6,362,664	[1]		6,362,664	[1]		6,197,821	[1]
Total recorded investment	6,435,123	[1]		6,435,123	[1]		6,281,022	[1]
Reserve for unfunded lending commitments [Abstract]
Reserve for unfunded lending commitments	10,700			10,700			11,900
Loans held for investment [Member] | Commercial loans [Member]
Changes in the allowance for loan losses [Roll Forward]
Balance at beginning of period	64,696			60,464
Provision for loan losses	9,283			13,597
Net charge-offs:
Charge-offs	(370)			(452)
Recoveries	0			0
Net charge-offs	(370)			(452)
Balance at end of period	73,609			73,609
Net charge-offs to average bank loans outstanding (annualized) (in hundredths)	0.04%			0.02%
Allowance for loan losses:
Individually evaluated for impairment	5,464			5,464			0
Collectively evaluated for impairment	68,145			68,145			60,464
Total allowance for loan losses	73,609			73,609
Loan category as a % of total recorded investment	59.00%			59.00%			52.00%
Recorded investment:
Individually evaluated for impairment	26,192	[1]		26,192	[1]		0	[1]
Collectively evaluated for impairment	3,770,347	[1]		3,770,347	[1]		3,232,723	[1]
Total recorded investment	3,796,539	[1]		3,796,539	[1]		3,232,723	[1]
Loans held for investment [Member] | CRE construction loans [Member]
Changes in the allowance for loan losses [Roll Forward]
Balance at beginning of period	2,745			4,473
Provision for loan losses	(2,318)			(4,046)
Net charge-offs:
Charge-offs	0			0
Recoveries	0			0
Net charge-offs	0			0
Balance at end of period	427			427
Net charge-offs to average bank loans outstanding (annualized) (in hundredths)	0.00%			0.00%
Allowance for loan losses:
Individually evaluated for impairment	0			0			0
Collectively evaluated for impairment	427			427			4,473
Total allowance for loan losses	427			427
Loan category as a % of total recorded investment	0.00%			0.00%			1.00%
Recorded investment:
Individually evaluated for impairment	0	[1]		0	[1]		0	[1]
Collectively evaluated for impairment	25,381	[1]		25,381	[1]		65,512	[1]
Total recorded investment	25,381	[1]		25,381	[1]		65,512	[1]
Loans held for investment [Member] | CRE loans [Member]
Changes in the allowance for loan losses [Roll Forward]
Balance at beginning of period	44,182			47,771
Provision for loan losses	(5,137)			925
Net charge-offs:
Charge-offs	(4,082)			(14,012)
Recoveries	780			1,059
Net charge-offs	(3,302)			(12,953)
Balance at end of period	35,743			35,743
Net charge-offs to average bank loans outstanding (annualized) (in hundredths)	1.73%			2.21%
Allowance for loan losses:
Individually evaluated for impairment	7,744			7,744			8,469
Collectively evaluated for impairment	27,999			27,999			39,302
Total allowance for loan losses	35,743			35,743
Loan category as a % of total recorded investment	12.00%			12.00%			15.00%
Recorded investment:
Individually evaluated for impairment	25,805	[1]		25,805	[1]		67,071	[1]
Collectively evaluated for impairment	757,492	[1]		757,492	[1]		870,598	[1]
Total recorded investment	783,297	[1]		783,297	[1]		937,669	[1]
Loans held for investment [Member] | Residential mortgage loans [Member]
Changes in the allowance for loan losses [Roll Forward]
Balance at beginning of period	34,469			34,297
Provision for loan losses	6,321			17,559
Net charge-offs:
Charge-offs	(5,243)			(17,348)
Recoveries	449			1,488
Net charge-offs	(4,794)			(15,860)
Balance at end of period	35,996			35,996
Net charge-offs to average bank loans outstanding (annualized) (in hundredths)	1.07%			1.12%
Allowance for loan losses:
Individually evaluated for impairment	2,704			2,704			2,812
Collectively evaluated for impairment	33,292			33,292			31,485
Total allowance for loan losses	35,996			35,996
Loan category as a % of total recorded investment	28.00%			28.00%			32.00%
Recorded investment:
Individually evaluated for impairment	20,462	[1]		20,462	[1]		16,130	[1]
Collectively evaluated for impairment	1,739,925	[1]		1,739,925	[1]		1,999,201	[1]
Total recorded investment	1,760,387	[1]		1,760,387	[1]		2,015,331	[1]
Loans held for investment [Member] | Consumer loans [Member]
Changes in the allowance for loan losses [Roll Forward]
Balance at beginning of period	19			56
Provision for loan losses	213			215
Net charge-offs:
Charge-offs	(215)			(255)
Recoveries	3			4
Net charge-offs	(212)			(251)
Balance at end of period	20			20
Net charge-offs to average bank loans outstanding (annualized) (in hundredths)	14.33%			4.82%
Allowance for loan losses:
Individually evaluated for impairment	0			0			0
Collectively evaluated for impairment	20			20			56
Total allowance for loan losses	20			20
Loan category as a % of total recorded investment	0.00%			0.00%			0.00%
Recorded investment:
Individually evaluated for impairment	0	[1]		0	[1]		0	[1]
Collectively evaluated for impairment	5,897	[1]		5,897	[1]		23,940	[1]
Total recorded investment	5,897	[1]		5,897	[1]		23,940	[1]
Loans held for sale [Member]
Changes in the allowance for loan losses [Roll Forward]
Balance at beginning of period	4			23
Provision for loan losses	1			(18)
Net charge-offs:
Charge-offs	0			0
Recoveries	0			0
Net charge-offs	0			0
Balance at end of period	5			5
Net charge-offs to average bank loans outstanding (annualized) (in hundredths)	0.00%			0.00%
Allowance for loan losses:
Individually evaluated for impairment	0			0			0
Collectively evaluated for impairment	5			5			23
Total allowance for loan losses	5			5
Loan category as a % of total recorded investment	1.00%			1.00%			0.00%
Recorded investment:
Individually evaluated for impairment	0	[1]		0	[1]		0	[1]
Collectively evaluated for impairment	63,622	[1]		63,622	[1]		5,847	[1]
Total recorded investment	$ 63,622	[1]		$ 63,622	[1]		$ 5,847	[1]

[1] Excludes any net unearned income and deferred expenses.