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Loans (Analysis of Impaired Loans) (Details) - Loans, Excluding Purchased Credit Impaired Loans [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) Modifications	Dec. 31, 2018 USD ($) Modifications	Dec. 31, 2017 USD ($) Modifications
Financing Receivable, Modifications, Number of Contracts | Modifications	24	34	60
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 8,633,955	$ 8,252,647
Recorded Investment of Loans Individually Measured for Specific Impairment	31,994	49,104
Recorded Investment	483	3,326
Unpaid Principal Balance	637	3,584
Related Allowance	22	31
Impaired Financing Receivable, Average Recorded Investment	42,731	65,461	$ 40,650
Impaired Financing Receivable, Interest Income, Accrual Method	$ 452	$ 1,138	$ 971
Commercial business: Secured loans [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	11	12	10
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 3,437,564	$ 3,286,416
Recorded Investment of Loans Individually Measured for Specific Impairment	24,083	26,285
Recorded Investment	3,286	6,350
Unpaid Principal Balance	3,851	8,460
Related Allowance	93	2,023
Impaired Financing Receivable, Average Recorded Investment	24,682	39,701	$ 20,282
Impaired Financing Receivable, Interest Income, Accrual Method	$ 202	$ 81	$ 60
Commercial business: Unsecured loans [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	0	0	1
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 129,671	$ 112,097
Recorded Investment of Loans Individually Measured for Specific Impairment	12	20
Recorded Investment	12	20
Unpaid Principal Balance	12	20
Related Allowance	0	0
Impaired Financing Receivable, Average Recorded Investment	16	191	$ 5
Impaired Financing Receivable, Interest Income, Accrual Method	$ 1	$ 2	$ 0
Real estate: One-to-four family residential [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	1	0	3
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 264,513	$ 235,138
Recorded Investment of Loans Individually Measured for Specific Impairment	382	888
Recorded Investment	299	325
Unpaid Principal Balance	588	798
Related Allowance	5	8
Impaired Financing Receivable, Average Recorded Investment	665	748	$ 730
Impaired Financing Receivable, Interest Income, Accrual Method	$ 42	$ 42	$ 49
Real estate: Commercial and multifamily residential: Commercial land [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	0	0	1
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 300,973	$ 283,451
Recorded Investment of Loans Individually Measured for Specific Impairment	2,217	2,226
Recorded Investment	1,592	0
Unpaid Principal Balance	1,601	0
Related Allowance	312	0
Impaired Financing Receivable, Average Recorded Investment	2,606	2,371	$ 2,079
Impaired Financing Receivable, Interest Income, Accrual Method	$ 31	$ 34	$ 0
Real estate: Commercial and multifamiIy residential: Income property [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	1	1	1
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 2,059,361	$ 1,917,522
Recorded Investment of Loans Individually Measured for Specific Impairment	0	2,954
Recorded Investment	0	99
Unpaid Principal Balance	0	165
Related Allowance	0	1
Impaired Financing Receivable, Average Recorded Investment	1,121	3,284	$ 4,314
Impaired Financing Receivable, Interest Income, Accrual Method	$ 0	$ 130	$ 51
Real estate: Commercial and multifamiIy residential: Owner occupied [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	0	0	1
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 1,797,682	$ 1,605,042
Recorded Investment of Loans Individually Measured for Specific Impairment	3,663	12,709
Recorded Investment	3,663	3,231
Unpaid Principal Balance	5,233	4,666
Related Allowance	29	69
Impaired Financing Receivable, Average Recorded Investment	10,681	9,730	$ 5,335
Impaired Financing Receivable, Interest Income, Accrual Method	168	720	445
Real estate construction: One-to-four family residential: Land and acquisition [Member]
Recorded Investment of Loans Collectively Measured for Contingency Provision	1,364	4,417
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	0	3
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	190,301	212,396
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	484	309
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	88,389	194,912
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	0	1
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 73,203	$ 87,063
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	3,240	$ 1,620
Impaired Financing Receivable, Interest Income, Accrual Method	$ 0	$ 0	$ 203
Consumer [Member]
Financing Receivable, Modifications, Number of Contracts | Modifications	11	21	42
Recorded Investment of Loans Collectively Measured for Contingency Provision	$ 290,934	$ 314,193
Recorded Investment of Loans Individually Measured for Specific Impairment	1,637	4,022
Impaired Financing Receivable, Average Recorded Investment	2,960	5,712	$ 5,973
Impaired Financing Receivable, Interest Income, Accrual Method	8	129	$ 163
Impaired Loans Without Recorded Allowance [Member]
Recorded Investment	22,659	35,753
Unpaid Principal Balance	30,813	40,716
Impaired Loans With Recorded Allowance [Member]
Recorded Investment	9,335	13,351
Unpaid Principal Balance	11,922	17,693
Related Allowance	461	2,132
Impaired Loans Without Recorded Allowance [Member]
Recorded Investment	1,154	696
Unpaid Principal Balance	1,310	704
Impaired Loans Without Recorded Allowance [Member] | Commercial business: Secured loans [Member]
Recorded Investment	20,797	19,935
Unpaid Principal Balance	28,658	24,404
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	83	563
Unpaid Principal Balance	182	575
Impaired Loans Without Recorded Allowance [Member] | Real estate: Commercial and multifamily residential: Commercial land [Member]
Recorded Investment	625	2,226
Unpaid Principal Balance	663	2,272
Impaired Loans Without Recorded Allowance [Member] | Real estate: Commercial and multifamiIy residential: Income property [Member]
Recorded Investment	0	2,855
Unpaid Principal Balance	0	3,011
Impaired Loans Without Recorded Allowance [Member] | Real estate: Commercial and multifamiIy residential: Owner occupied [Member]
Recorded Investment	0	9,478
Unpaid Principal Balance	0	9,750
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	0
Unpaid Principal Balance	0	0
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	0
Unpaid Principal Balance	$ 0	$ 0

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- Definition

The balance of financing receivables that were collectively evaluated for impairment.

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