Allowance for Losses on Loans - Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	$ 113,494	$ 106,829
Charge-offs	(404)	(2,121)
Recoveries	5,700	3,193
Provision & Transfers	(334)	0
Ending Allowance	118,456	107,901
Single-family residential
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	37,796	47,347
Charge-offs	(115)	(1,139)
Recoveries	151	2,466
Provision & Transfers	374	(918)
Ending Allowance	38,206	47,756
Construction
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	19,838	6,680
Charge-offs	0	0
Recoveries	0	155
Provision & Transfers	2,096	179
Ending Allowance	21,934	7,014
Construction - custom
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	1,080	990
Charge-offs	0	(60)
Recoveries	0	0
Provision & Transfers	30	132
Ending Allowance	1,110	1,062
Land - acquisition & development
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	6,023	5,781
Charge-offs	(20)	0
Recoveries	4,018	35
Provision & Transfers	(3,356)	962
Ending Allowance	6,665	6,778
Land - consumer lot loans
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	2,535	2,946
Charge-offs	(17)	(408)
Recoveries	70	0
Provision & Transfers	(87)	463
Ending Allowance	2,501	3,001
Multi-family
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	6,925	5,304
Charge-offs	0	0
Recoveries	0	0
Provision & Transfers	704	(257)
Ending Allowance	7,629	5,047
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	8,588	8,960
Charge-offs	(11)	(23)
Recoveries	356	123
Provision & Transfers	1,235	1,284
Ending Allowance	10,168	10,344
Commercial & industrial
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	28,008	24,980
Charge-offs	(58)	(248)
Recoveries	725	1
Provision & Transfers	(939)	(637)
Ending Allowance	27,736	24,096
HELOC
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	813	902
Charge-offs	(37)	(1)
Recoveries	1	21
Provision & Transfers	55	(102)
Ending Allowance	832	820
Consumer
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Allowance	1,888	2,939
Charge-offs	(146)	(242)
Recoveries	379	392
Provision & Transfers	(446)	(1,106)
Ending Allowance	$ 1,675	$ 1,983

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=66008989&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=66008989&loc=SL6953423-111524

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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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=66008989&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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