Allowance for Losses on Loans - Allowance for Credit Losses (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	$ 108,700	$ 118,158	$ 112,347	$ 116,741
Charge-offs	(2,517)	(4,775)	(5,126)	(9,586)
Recoveries	5,640	6,298	9,091	17,126
Provision & Transfers	(3,500)	(4,750)	(7,989)	(9,350)
Ending Allowance	108,323	114,931	108,323	114,931
Single-Family Residential [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	55,495	67,692	62,763	64,184
Charge-offs	(1,409)	(2,444)	(3,103)	(4,777)
Recoveries	4,122	2,088	6,675	10,913
Provision & Transfers	(3,446)	(3,988)	(11,573)	(6,972)
Ending Allowance	54,762	63,348	54,762	63,348
Construction - Speculative [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	5,451	8,142	6,742	8,407
Charge-offs	0	(488)	(388)	(938)
Recoveries	75	0	75	95
Provision & Transfers	(81)	(881)	(984)	(791)
Ending Allowance	5,445	6,773	5,445	6,773
Construction - Custom [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	965	1,474	1,695	882
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision & Transfers	3	125	(727)	717
Ending Allowance	968	1,599	968	1,599
Land - Acquisition & Development [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	6,671	7,084	5,592	9,165
Charge-offs	0	(85)	(38)	(541)
Recoveries	204	299	205	738
Provision & Transfers	530	(1,271)	1,646	(3,335)
Ending Allowance	7,405	6,027	7,405	6,027
Land - Consumer Lot Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	3,113	3,274	3,077	3,552
Charge-offs	(52)	(231)	(87)	(474)
Recoveries	34	0	34	22
Provision & Transfers	(60)	(69)	11	(126)
Ending Allowance	3,035	2,974	3,035	2,974
Multi-Family [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	4,500	4,109	4,248	3,816
Charge-offs	0	0	0	0
Recoveries	0	0	220	0
Provision & Transfers	173	78	205	371
Ending Allowance	4,673	4,187	4,673	4,187
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	5,872	5,868	7,548	5,595
Charge-offs	0	(73)	(27)	(73)
Recoveries	453	0	481	0
Provision & Transfers	409	129	(1,268)	402
Ending Allowance	6,734	5,924	6,734	5,924
Commercial & Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	23,328	16,505	16,527	16,614
Charge-offs	(355)	(444)	(355)	(692)
Recoveries	18	2,852	52	3,273
Provision & Transfers	(1,845)	1,490	4,922	1,208
Ending Allowance	21,146	20,403	21,146	20,403
HELOC [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	892	943	928	1,002
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision & Transfers	(42)	32	(78)	(27)
Ending Allowance	850	975	850	975
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	2,413	3,067	3,227	3,524
Charge-offs	(701)	(1,010)	(1,128)	(2,091)
Recoveries	734	1,059	1,349	2,085
Provision & Transfers	859	(395)	(143)	(797)
Ending Allowance	$ 3,305	$ 2,721	$ 3,305	$ 2,721

A valuation allowance for financing receivables that are expected to be uncollectible.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953423-111524

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- Definition

Amount of recovery of financing receivables doubtful of collection that were previously charged off.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (c)(4)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953423-111524

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- Definition

Amount of direct write-downs of financing receivables charged against the allowance.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (c)(3)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953423-111524

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- Definition

Financing Receivable, Allowance for Credit Losses, Provision and Transfers

+ References

No definition available.

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