Allowance for Losses on Loans (Credit Risk Profile Based on Payment Activity) (Details) (USD $)	Jun. 30, 2014	Sep. 30, 2013	Jun. 30, 2013
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	$ 8,447,709,000	$ 7,990,545,000
Nonaccrual loans by portfolio segment	94,226,000	131,299,000	131,299,000
Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	8,072,881,000	7,509,967,000
Grade as percentage of total gross loans	98.80%	98.30%
Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	162,357,000		213,616,000
Grade as percentage of total gross loans	1.10%		1.60%
Nonaccrual loans by portfolio segment	94,226,000	131,299,000
Grade as a percentage of total gross loans	1.20%	1.70%
Single-Family Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	5,479,111,000	5,373,950,000
Nonaccrual loans by portfolio segment	78,317,000	100,460,000
Single-Family Residential [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	5,388,454,000	5,258,688,000
Grade as percentage of total gross loans	98.60%	98.10%
Single-Family Residential [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans by portfolio segment	78,317,000	100,460,000
Grade as a percentage of total gross loans	1.40%	1.90%
Construction - Speculative [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	126,926,000	130,778,000
Nonaccrual loans by portfolio segment	1,966,000	4,560,000
Construction - Speculative [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	124,960,000	126,218,000
Grade as percentage of total gross loans	98.50%	96.50%
Construction - Speculative [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans by portfolio segment	1,966,000	4,560,000
Grade as a percentage of total gross loans	1.50%	3.50%
Construction - Custom [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	372,789,000	302,722,000
Nonaccrual loans by portfolio segment	143,000	0
Construction - Custom [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	372,646,000	302,722,000
Grade as percentage of total gross loans	100.00%	100.00%
Construction - Custom [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans by portfolio segment	143,000	0
Grade as a percentage of total gross loans	0.00%	0.00%
Land - Acquisition & Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	91,058,000	81,660,000
Nonaccrual loans by portfolio segment	2,295,000	2,903,000
Land - Acquisition & Development [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	86,024,000	74,872,000
Grade as percentage of total gross loans	97.40%	96.30%
Land - Acquisition & Development [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans by portfolio segment	2,295,000	2,903,000
Grade as a percentage of total gross loans	2.60%	3.70%
Land - Consumer Lot Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	114,573,000	124,984,000
Nonaccrual loans by portfolio segment	1,879,000	3,337,000
Land - Consumer Lot Loans [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	110,040,000	118,334,000
Grade as percentage of total gross loans	98.30%	97.30%
Land - Consumer Lot Loans [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans by portfolio segment	1,879,000	3,337,000
Grade as a percentage of total gross loans	1.70%	2.70%
Multi-Family [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	896,799,000	835,598,000
Nonaccrual loans by portfolio segment	2,103,000	6,573,000
Multi-Family [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	891,639,000	825,111,000
Grade as percentage of total gross loans	99.80%	99.20%
Multi-Family [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans by portfolio segment	2,103,000	6,573,000
Grade as a percentage of total gross loans	0.20%	0.80%
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	693,421,000	625,293,000
Nonaccrual loans by portfolio segment	5,442,000	11,736,000
Commercial Real Estate [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	518,408,000	389,423,000
Grade as percentage of total gross loans	99.00%	97.10%
Commercial Real Estate [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans by portfolio segment	5,442,000	11,736,000
Grade as a percentage of total gross loans	1.00%	2.90%
Commercial & Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	398,181,000	326,450,000
Nonaccrual loans by portfolio segment	516,000	477,000
Commercial & Industrial [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	333,036,000	256,525,000
Grade as percentage of total gross loans	99.80%	99.80%
Commercial & Industrial [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans by portfolio segment	516,000	477,000
Grade as a percentage of total gross loans	0.20%	0.20%
HELOC [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	136,304,000	133,631,000
Nonaccrual loans by portfolio segment	970,000	263,000
HELOC [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	116,207,000	111,923,000
Grade as percentage of total gross loans	99.20%	99.80%
HELOC [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans by portfolio segment	970,000	263,000
Grade as a percentage of total gross loans	0.80%	0.20%
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	138,547,000	55,479,000
Nonaccrual loans by portfolio segment	595,000	990,000
Consumer [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	131,467,000	46,151,000
Grade as percentage of total gross loans	99.50%	97.90%
Consumer [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans by portfolio segment	$ 595,000	$ 990,000
Grade as a percentage of total gross loans	0.50%	2.10%