Loans (Analysis of Impaired Loans) (Details) - Loans, Excluding Purchased Credit Impaired Loans [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 6,345,954		$ 6,345,954		$ 6,042,304
Recorded Investment of Loans Individually Measured for Specific Impairment	45,575		45,575		25,459
Recorded Investment	38,905		38,905		17,592
Unpaid Principal Balance	48,079		48,079		27,228
Related Allowance	102		102		761
Average Recorded Investment Impaired Loans	42,623	$ 18,556	33,508	$ 20,502
Interest Recognized on Impaired Loans	374	54	664	125
Secured Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment of Loans Collectively Measured for Contingency Provision	2,614,647		2,614,647		2,442,772
Recorded Investment of Loans Individually Measured for Specific Impairment	21,399		21,399		8,818
Recorded Investment	0		0		2,414
Unpaid Principal Balance	0		0		2,484
Related Allowance	0		0		664
Average Recorded Investment Impaired Loans	22,395	6,909	15,349	9,506
Interest Recognized on Impaired Loans	2	15	25	48
Unsecured Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment of Loans Collectively Measured for Contingency Provision	93,924		93,924		94,737
Recorded Investment of Loans Individually Measured for Specific Impairment	0		0		0
Recorded Investment	0		0		0
Unpaid Principal Balance	0		0		0
Related Allowance	0		0		0
Average Recorded Investment Impaired Loans	0	0	0	0
Interest Recognized on Impaired Loans	0	0	0	0
One-to-Four Family Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment of Loans Collectively Measured for Contingency Provision	173,562		173,562		167,403
Recorded Investment of Loans Individually Measured for Specific Impairment	928		928		529
Recorded Investment	459		459		435
Unpaid Principal Balance	736		736		693
Related Allowance	26		26		12
Average Recorded Investment Impaired Loans	856	617	688	796
Interest Recognized on Impaired Loans	15	5	37	8
Commercial Land [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment of Loans Collectively Measured for Contingency Provision	283,355		283,355		270,106
Recorded Investment of Loans Individually Measured for Specific Impairment	2,299		2,299		708
Recorded Investment	0		0		0
Unpaid Principal Balance	0		0		0
Related Allowance	0		0		0
Average Recorded Investment Impaired Loans	2,549	708	2,026	354
Interest Recognized on Impaired Loans	0	0	0	0
Income Property Multifamily [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment of Loans Collectively Measured for Contingency Provision	1,378,127		1,378,127		1,365,321
Recorded Investment of Loans Individually Measured for Specific Impairment	4,771		4,771		4,425
Recorded Investment	519		519		540
Unpaid Principal Balance	523		523		544
Related Allowance	25		25		27
Average Recorded Investment Impaired Loans	4,214	1,939	4,137	2,010
Interest Recognized on Impaired Loans	21	8	27	19
Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment of Loans Collectively Measured for Contingency Provision	1,134,945		1,134,945		1,054,564
Recorded Investment of Loans Individually Measured for Specific Impairment	5,663		5,663		5,414
Recorded Investment	0		0		0
Unpaid Principal Balance	0		0		0
Related Allowance	0		0		0
Average Recorded Investment Impaired Loans	4,530	4,486	4,496	5,001
Interest Recognized on Impaired Loans	127	0	319	0
Land And Acquisition [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment of Loans Collectively Measured for Contingency Provision	6,813		6,813		11,542
Recorded Investment of Loans Individually Measured for Specific Impairment	0		0		14
Recorded Investment	0		0		14
Unpaid Principal Balance	0		0		102
Related Allowance	0		0		1
Average Recorded Investment Impaired Loans	0	103	4	245
Interest Recognized on Impaired Loans	0	1	0	4
Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment of Loans Collectively Measured for Contingency Provision	137,920		137,920		109,293
Recorded Investment of Loans Individually Measured for Specific Impairment	0		0		336
Recorded Investment	0		0		0
Unpaid Principal Balance	0		0		0
Related Allowance	0		0		0
Average Recorded Investment Impaired Loans	0	449	84	506
Interest Recognized on Impaired Loans	0	0	0	0
Income Property Multifamily Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment of Loans Collectively Measured for Contingency Provision	172,112		172,112		103,779
Recorded Investment of Loans Individually Measured for Specific Impairment	0		0		0
Recorded Investment	0		0		0
Unpaid Principal Balance	0		0		0
Related Allowance	0		0		0
Owner Occupied Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment of Loans Collectively Measured for Contingency Provision	35,511		35,511		103,480
Recorded Investment of Loans Individually Measured for Specific Impairment	4,050		4,050		0
Recorded Investment	0		0		0
Unpaid Principal Balance	0		0		0
Related Allowance	0		0		0
Average Recorded Investment Impaired Loans	2,025	0	1,012	0
Interest Recognized on Impaired Loans	151	0	151	0
Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment of Loans Collectively Measured for Contingency Provision	315,038		315,038		319,307
Recorded Investment of Loans Individually Measured for Specific Impairment	6,465		6,465		5,215
Recorded Investment	5,692		5,692		4,464
Unpaid Principal Balance	5,982		5,982		4,558
Related Allowance	51		51		57
Average Recorded Investment Impaired Loans	6,054	3,345	5,712	2,084
Interest Recognized on Impaired Loans	58	$ 25	105	$ 46
Impaired Loans With Recorded Allowance [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment	6,670		6,670		7,867
Unpaid Principal Balance	7,241		7,241		8,381
Impaired Loans Without Recorded Allowance [Member] | Secured Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment	21,399		21,399		6,404
Unpaid Principal Balance	26,655		26,655		12,831
Impaired Loans Without Recorded Allowance [Member] | Unsecured Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment	0		0		0
Unpaid Principal Balance	0		0		0
Impaired Loans Without Recorded Allowance [Member] | One-to-Four Family Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment	469		469		94
Unpaid Principal Balance	1,030		1,030		291
Impaired Loans Without Recorded Allowance [Member] | Commercial Land [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment	2,299		2,299		708
Unpaid Principal Balance	2,287		2,287		687
Impaired Loans Without Recorded Allowance [Member] | Income Property Multifamily [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment	4,252		4,252		3,885
Unpaid Principal Balance	4,570		4,570		4,148
Impaired Loans Without Recorded Allowance [Member] | Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment	5,663		5,663		5,414
Unpaid Principal Balance	8,573		8,573		8,102
Impaired Loans Without Recorded Allowance [Member] | Land And Acquisition [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment	0		0		0
Unpaid Principal Balance	0		0		0
Impaired Loans Without Recorded Allowance [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment	0		0		336
Unpaid Principal Balance	0		0		336
Impaired Loans Without Recorded Allowance [Member] | Income Property Multifamily Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment	0		0		0
Unpaid Principal Balance	0		0		0
Impaired Loans Without Recorded Allowance [Member] | Owner Occupied Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment	4,050		4,050		0
Unpaid Principal Balance	4,050		4,050		0
Impaired Loans Without Recorded Allowance [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment	773		773		751
Unpaid Principal Balance	$ 914		$ 914		$ 833