Loans (Analysis of Impaired Loans) (Details) - Loans, Excluding Purchased Credit Impaired Loans [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Modifications	Dec. 31, 2017 USD ($) Modifications	Dec. 31, 2016 USD ($) Modifications
Financing Receivable, Modifications, Number of Contracts | Modifications	34	60	54
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 8,252,647	$ 8,176,782
Recorded Investment of Loans Individually Measured for Specific Impairment	49,104	69,205
Recorded Investment	3,326	5,303
Unpaid Principal Balance	3,584	5,568
Related Allowance	31	199
Impaired Financing Receivable, Average Recorded Investment	65,461	40,650	$ 21,493
Impaired Financing Receivable, Interest Income, Accrual Method	$ 1,138	$ 971	$ 237
Commercial business: Secured loans [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	12	10	9
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 3,286,416	$ 3,195,649
Recorded Investment of Loans Individually Measured for Specific Impairment	26,285	40,012
Recorded Investment	6,350	3,808
Unpaid Principal Balance	8,460	3,937
Related Allowance	2,023	1,867
Impaired Financing Receivable, Average Recorded Investment	39,701	20,282	$ 9,368
Impaired Financing Receivable, Interest Income, Accrual Method	$ 81	$ 60	$ 79
Commercial business: Unsecured loans [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	0	1	0
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 112,097	$ 124,150
Recorded Investment of Loans Individually Measured for Specific Impairment	20	25
Recorded Investment	20	25
Unpaid Principal Balance	20	24
Related Allowance	0	3
Impaired Financing Receivable, Average Recorded Investment	191	5	$ 0
Impaired Financing Receivable, Interest Income, Accrual Method	$ 2	$ 0	$ 0
Real estate: One-to-four family residential [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	0	3	3
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 235,138	$ 185,659
Recorded Investment of Loans Individually Measured for Specific Impairment	888	895
Recorded Investment	325	867
Unpaid Principal Balance	798	1,408
Related Allowance	8	103
Impaired Financing Receivable, Average Recorded Investment	748	730	$ 743
Impaired Financing Receivable, Interest Income, Accrual Method	$ 42	$ 49	$ 10
Real estate: Commercial and multifamily residential: Commercial land [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	0	1	0
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 283,451	$ 293,694
Recorded Investment of Loans Individually Measured for Specific Impairment	2,226	2,287
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Impaired Financing Receivable, Average Recorded Investment	2,371	2,079	$ 425
Impaired Financing Receivable, Interest Income, Accrual Method	$ 34	$ 0	$ 0
Real estate: Commercial and multifamiIy residential: Income property [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	1	1	0
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 1,917,522	$ 1,901,313
Recorded Investment of Loans Individually Measured for Specific Impairment	2,954	5,023
Recorded Investment	99	2,768
Unpaid Principal Balance	165	3,328
Related Allowance	1	185
Impaired Financing Receivable, Average Recorded Investment	3,284	4,314	$ 2,492
Impaired Financing Receivable, Interest Income, Accrual Method	$ 130	$ 51	$ 26
Real estate: Commercial and multifamiIy residential: Owner occupied [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	0	1	1
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 1,605,042	$ 1,591,298
Recorded Investment of Loans Individually Measured for Specific Impairment	12,709	8,688
Recorded Investment	3,231	77
Unpaid Principal Balance	4,666	80
Related Allowance	69	3
Impaired Financing Receivable, Average Recorded Investment	9,730	5,335	$ 5,084
Impaired Financing Receivable, Interest Income, Accrual Method	720	445	0
Real estate construction: One-to-four family residential: Land and acquisition [Member]
Recorded Investment of Loans Collectively Measured for Contingency Provision	4,417	9,907
Recorded Investment of Loans Individually Measured for Specific Impairment	0	0
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Impaired Financing Receivable, Average Recorded Investment	0	3	199
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	0
Real estate construction: One-to-four family residential: Residential construction [Member]
Recorded Investment of Loans Collectively Measured for Contingency Provision	212,396	188,481
Recorded Investment of Loans Individually Measured for Specific Impairment	0	1,210
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Impaired Financing Receivable, Average Recorded Investment	484	309	472
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	$ 0
Real estate construction: Commercial and multifamily residential: Income property [Member]
Recorded Investment of Loans Collectively Measured for Contingency Provision	194,912	293,028
Recorded Investment of Loans Individually Measured for Specific Impairment	0	0
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	$ 0	$ 0
Real estate construction: Commercial and multifamily residential: Owner occupied [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	0	1	0
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 87,063	$ 68,393
Recorded Investment of Loans Individually Measured for Specific Impairment	0	4,050
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Impaired Financing Receivable, Average Recorded Investment	3,240	1,620	$ 0
Impaired Financing Receivable, Interest Income, Accrual Method	$ 0	$ 203	$ 0
Consumer [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	21	42	41
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 314,193	$ 325,210
Recorded Investment of Loans Individually Measured for Specific Impairment	4,022	7,015
Impaired Financing Receivable, Average Recorded Investment	5,712	5,973	$ 2,710
Impaired Financing Receivable, Interest Income, Accrual Method	129	163	$ 122
Impaired Loans Without Recorded Allowance [Member]
Recorded Investment	35,753	56,357
Unpaid Principal Balance	40,716	64,735
Impaired Loans With Recorded Allowance [Member]
Recorded Investment	13,351	12,848
Unpaid Principal Balance	17,693	14,345
Related Allowance	2,132	2,360
Impaired Loans Without Recorded Allowance [Member]
Recorded Investment	696	1,712
Unpaid Principal Balance	704	1,864
Impaired Loans Without Recorded Allowance [Member] | Commercial business: Secured loans [Member]
Recorded Investment	19,935	36,204
Unpaid Principal Balance	24,404	42,314
Impaired Loans Without Recorded Allowance [Member] | Commercial business: Unsecured loans [Member]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Impaired Loans Without Recorded Allowance [Member] | Real estate: One-to-four family residential [Member]
Recorded Investment	563	28
Unpaid Principal Balance	575	337
Impaired Loans Without Recorded Allowance [Member] | Real estate: Commercial and multifamily residential: Commercial land [Member]
Recorded Investment	2,226	2,287
Unpaid Principal Balance	2,272	2,282
Impaired Loans Without Recorded Allowance [Member] | Real estate: Commercial and multifamiIy residential: Income property [Member]
Recorded Investment	2,855	2,255
Unpaid Principal Balance	3,011	2,601
Impaired Loans Without Recorded Allowance [Member] | Real estate: Commercial and multifamiIy residential: Owner occupied [Member]
Recorded Investment	9,478	8,611
Unpaid Principal Balance	9,750	10,077
Impaired Loans Without Recorded Allowance [Member] | Real estate construction: One-to-four family residential: Land and acquisition [Member]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Impaired Loans Without Recorded Allowance [Member] | Real estate construction: One-to-four family residential: Residential construction [Member]
Recorded Investment	0	1,210
Unpaid Principal Balance	0	1,210
Impaired Loans Without Recorded Allowance [Member] | Real estate construction: Commercial and multifamily residential: Income property [Member]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Impaired Loans Without Recorded Allowance [Member] | Real estate construction: Commercial and multifamily residential: Owner occupied [Member]
Recorded Investment	0	4,050
Unpaid Principal Balance	$ 0	$ 4,050