Covered Assets - Acquired Impaired and Non-impaired Covered Loans (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
Mar. 31, 2015	Sep. 30, 2014
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Accretion, carrying amount of loans	$ 284	$ 802
Acquired Impaired Loans [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period, accretable yield	64,534	78,277
Balance at beginning of period, carrying amount of loans	78,055	138,091
Reclassification from nonaccretable balance, net, accretable yield	6,307	10,186
Reclassification from nonaccretable balance, net, Carrying Amount of Loans	0	(2,069)
Accretion, accretable yield	(9,392)	(23,929)
Accretion, carrying amount of loans	9,392	23,929
Transfers to REO, accretable yield	0	0
Transfers to REO, carrying amount of loans	(936)	(8,943)
Payments received, net, accretable yield	0	0
Payments received, net, carrying amount of loans	(11,049)	(72,953)
Balance at end of period, accretable yield	61,449	64,534
Balance at end of period, carrying amount of loans	75,462	78,055
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, accretable yield	10,259	17,263
Balance at beginning of period, carrying amount of loans	98,422	157,856
Reclassification from nonaccretable balance, net, accretable yield	0	0
Reclassification from nonaccretable balance, net, Carrying Amount of Loans	0	0
Accretion, accretable yield	(4,016)	(7,004)
Accretion, carrying amount of loans	4,016	7,004
Transfers to REO, accretable yield	0	0
Transfers to REO, carrying amount of loans	0	0
Payments received, net, accretable yield	0	0
Payments received, net, carrying amount of loans	(40,452)	(66,438)
Balance at end of period, accretable yield	6,243	10,259
Balance at end of period, carrying amount of loans	$ 61,986	$ 98,422

Amount of the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 15

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=27045933&loc=d3e13503-111538

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(2)

-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

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- Definition

Amount of decrease from accretion of the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality.

+ References

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- Definition

Amount of increase of reclassification from nonaccretable difference to the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality.

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- Definition

The recorded balance, net of any applicable reductions (for example, unamortized accretable yield and allowance for loan losses). This relates to loans not accounted for debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 15

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=27045933&loc=d3e13503-111538

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

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- Definition

Certain Loans Acquired in Transfer not Accounted for as Debt Securities Accretable Yield, Payments

+ References

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- Definition

Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Transfers to Real Estate Owned

+ References

No definition available.

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- Definition

Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Payments

+ References

No definition available.

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- Definition

Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Reclassifications from Nonaccretable Difference

+ References

No definition available.

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- Definition

Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Transfers to Real Estate Owned

+ References

No definition available.

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- Definition

FDIC Indemnification Asset, Discount Accretion

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- Details

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