Loans (Analysis of the Aged Loan Portfolio) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans	$ 66,189
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans	4,149
Commercial business: Secured loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans	45,410
Commercial business: Unsecured loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans	50
Real estate: One-to-four family residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans	785
Real estate: Commercial and multifamily residential: Commercial land [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans	2,628
Real estate: Commercial and multifamiIy residential: Owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans	7,029
Real estate construction: One-to-four family residential: Land and acquisition [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans	25
Real estate construction: One-to-four family residential: Residential construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans	1,829
Real estate: Commercial and multifamiIy residential: Income property [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans	4,284
Loans, Excluding Purchased Credit Impaired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	8,163,583	$ 6,031,078
Total Past Due	16,215	8,929
Nonaccrual Loans	66,189	27,756
Loans Receivable, Net	8,245,987	6,067,763
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: Commercial and multifamily residential: Income property [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	293,028	103,779
Total Past Due	0	0
Nonaccrual Loans	0	0
Loans Receivable, Net	293,028	103,779
Loans, Excluding Purchased Credit Impaired Loans [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	325,928	318,369
Total Past Due	2,148	2,270
Nonaccrual Loans	4,149	3,883
Loans Receivable, Net	332,225	324,522
Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial business: Secured loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	3,185,321	2,439,250
Total Past Due	4,930	816
Nonaccrual Loans	45,410	11,524
Loans Receivable, Net	3,235,661	2,451,590
Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial business: Unsecured loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	123,524	94,118
Total Past Due	601	588
Nonaccrual Loans	50	31
Loans Receivable, Net	124,175	94,737
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: One-to-four family residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	184,256	164,416
Total Past Due	1,513	2,948
Nonaccrual Loans	785	568
Loans Receivable, Net	186,554	167,932
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamily residential: Commercial land [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	292,680	269,816
Total Past Due	673	64
Nonaccrual Loans	2,628	934
Loans Receivable, Net	295,981	270,814
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamiIy residential: Owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	1,590,004	1,052,078
Total Past Due	2,953	1,652
Nonaccrual Loans	7,029	6,248
Loans Receivable, Net	1,599,986	1,059,978
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: One-to-four family residential: Land and acquisition [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	9,882	11,542
Total Past Due	0	0
Nonaccrual Loans	25	14
Loans Receivable, Net	9,907	11,556
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: One-to-four family residential: Residential construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	187,862	109,080
Total Past Due	0	0
Nonaccrual Loans	1,829	549
Loans Receivable, Net	189,691	109,629
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamiIy residential: Income property [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	1,898,655	1,365,150
Total Past Due	3,397	591
Nonaccrual Loans	4,284	4,005
Loans Receivable, Net	1,906,336	1,369,746
Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: Commercial and multifamily residential: Owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	72,443	103,480
Total Past Due	0	0
Nonaccrual Loans	0	0
Loans Receivable, Net	72,443	103,480
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	10,190	7,772
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: Commercial and multifamily residential: Income property [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,446	2,035
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial business: Secured loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,530	806
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial business: Unsecured loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	100	287
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: One-to-four family residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,111	2,448
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamily residential: Commercial land [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	92	64
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamiIy residential: Owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,485	1,652
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: One-to-four family residential: Land and acquisition [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: One-to-four family residential: Residential construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamiIy residential: Income property [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,426	480
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: Commercial and multifamily residential: Owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5,444	1,157
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: Commercial and multifamily residential: Income property [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	702	235
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial business: Secured loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,400	10
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial business: Unsecured loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	501	301
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: One-to-four family residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	402	500
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamily residential: Commercial land [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamiIy residential: Owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	468	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: One-to-four family residential: Land and acquisition [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: One-to-four family residential: Residential construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamiIy residential: Income property [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	971	111
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: Commercial and multifamily residential: Owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	581	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: Commercial and multifamily residential: Income property [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial business: Secured loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Commercial business: Unsecured loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: One-to-four family residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamily residential: Commercial land [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	581	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamiIy residential: Owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: One-to-four family residential: Land and acquisition [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: One-to-four family residential: Residential construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate: Commercial and multifamiIy residential: Income property [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans, Excluding Purchased Credit Impaired Loans [Member] | Real estate construction: Commercial and multifamily residential: Owner occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 0	$ 0