Covered Assets (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012
Covered assets	$ 416,624		$ 317,925
Loans and Leases Receivable, Covered Loans, Gross	465,882		373,455
Discount balance related to acquired loans	85,288		85,079
FDIC Indemnification Asset Movement Analysis [Roll Forward]
Balance at beginning of period	87,571		101,634
Additions	17,364	[1]	3,284	[1]
Payments made (received)	(4,566)		(3,456)
Amortization	(10,224)		(15,510)
Accretion, Carrying Amount of Loans	270		1,619
Balance at end of period	90,415		87,571
Acquired Impaired Assets [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period, AccretableYield	50,902		37,072
Balance at beginning of period, Carrying Amount of Loans	74,953		116,061
Additions, AccretableYield	0	[1]
Additions, Carrying Amount of Loans	107,075	[1]
Reclassification from nonaccretable balance, net, AccretableYield			34,690
Reclassification from nonaccretable balance, net, Carrying Amount of Loans			0
Accretion, AccretableYield	(12,487)		(20,860)
Transfers to REO, AccretableYield	0		0
Transfers to REO, Carrying Amount of Loans	(2,512)		(15,905)
Payments received, net, AccretableYield	0		0
Payments received, net, Carrying Amount of Loans	(9,591)		(46,063)
Balance at end of period, AccretableYield	38,415		50,902
Balance at end of period, Carrying Amount of Loans	182,412		74,953
FDIC Indemnification Asset Movement Analysis [Roll Forward]
Accretion, Carrying Amount of Loans	12,487		20,860
Acquired Non Impaired Assets [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period, AccretableYield	23,789		30,370
Balance at beginning of period, Carrying Amount of Loans	213,423		269,888
Additions, AccretableYield	0	[1]
Additions, Carrying Amount of Loans	0	[1]
Reclassification from nonaccretable balance, net, AccretableYield			0
Reclassification from nonaccretable balance, net, Carrying Amount of Loans			0
Accretion, AccretableYield	(1,803)		(6,581)
Transfers to REO, AccretableYield	0		0
Transfers to REO, Carrying Amount of Loans	0		0
Payments received, net, AccretableYield	0		0
Payments received, net, Carrying Amount of Loans	(17,044)		(63,046)
Balance at end of period, AccretableYield	21,986		23,789
Balance at end of period, Carrying Amount of Loans	198,182		213,423
FDIC Indemnification Asset Movement Analysis [Roll Forward]
Accretion, Carrying Amount of Loans	$ 1,803		$ 6,581

[1] includes FDIC covered loans which were acquired as part of the South Valley acquisition.