Allowance for Losses on Loans (Credit Risk Profile Based on Payment Activity) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	$ 8,110,309	$ 7,990,545
Nonaccrual loans by portfolio segment	114,717	131,299	163,116
Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	7,674,137	7,509,967
Grade as percentage of total gross loans	98.50%	98.30%
Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	197,910		264,219
Grade as percentage of total gross loans	1.37%		2.02%
Nonaccrual loans by portfolio segment	114,717	131,299
Grade as a percetage of total gross loans	1.50%	1.70%
Single-Family Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	5,436,083	5,373,950
Nonaccrual loans by portfolio segment	89,075	100,460
Single-Family Residential [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	5,332,821	5,258,688
Grade as percentage of total gross loans	98.40%	98.10%
Single-Family Residential [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans by portfolio segment	89,075	100,460
Grade as a percetage of total gross loans	1.60%	1.90%
Construction - Speculative [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	135,868	130,778
Nonaccrual loans by portfolio segment	3,053	4,560
Construction - Speculative [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	132,815	126,218
Grade as percentage of total gross loans	97.80%	96.50%
Construction - Speculative [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans by portfolio segment	3,053	4,560
Grade as a percetage of total gross loans	2.20%	3.50%
Construction - Custom [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	333,954	302,722
Nonaccrual loans by portfolio segment	0	0
Construction - Custom [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	333,954	302,722
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	0	0
Grade as a percetage of total gross loans	0.00%	0.00%
Land - Acquisition & Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	75,506	81,660
Nonaccrual loans by portfolio segment	2,813	2,903
Land - Acquisition & Development [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	69,262	74,872
Grade as percentage of total gross loans	96.10%	96.30%
Land - Acquisition & Development [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans by portfolio segment	2,813	2,903
Grade as a percetage of total gross loans	3.90%	3.70%
Land - Consumer Lot Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	122,467	124,984
Nonaccrual loans by portfolio segment	3,548	3,337
Land - Consumer Lot Loans [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	115,658	118,334
Grade as percentage of total gross loans	97.00%	97.30%
Land - Consumer Lot Loans [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans by portfolio segment	3,548	3,337
Grade as a percetage of total gross loans	3.00%	2.70%
Multi-Family [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	846,116	835,598
Nonaccrual loans by portfolio segment	2,494	6,573
Multi-Family [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	839,849	825,111
Grade as percentage of total gross loans	99.70%	99.20%
Multi-Family [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans by portfolio segment	2,494	6,573
Grade as a percetage of total gross loans	0.30%	0.80%
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	622,240	625,293
Nonaccrual loans by portfolio segment	11,613	11,736
Commercial Real Estate [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	421,748	389,423
Grade as percentage of total gross loans	97.30%	97.10%
Commercial Real Estate [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans by portfolio segment	11,613	11,736
Grade as a percetage of total gross loans	2.70%	2.90%
Commercial & Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	354,166	326,450
Nonaccrual loans by portfolio segment	655	477
Commercial & Industrial [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	273,777	256,525
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	655	477
Grade as a percetage of total gross loans	0.20%	0.20%
HELOC [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	131,949	133,631
Nonaccrual loans by portfolio segment	471	263
HELOC [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	111,106	111,923
Grade as percentage of total gross loans	99.60%	99.80%
HELOC [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans by portfolio segment	471	263
Grade as a percetage of total gross loans	0.40%	0.20%
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	51,960	55,479
Nonaccrual loans by portfolio segment	995	990
Consumer [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans receivable, gross	43,147	46,151
Grade as percentage of total gross loans	97.70%	97.90%
Consumer [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans by portfolio segment	$ 995	$ 990
Grade as a percetage of total gross loans	2.30%	0.20%