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Loans (Analysis of Impaired Loans) (Details) - Loans, Excluding Purchased Credit Impaired Loans [Member] $ in Thousands | 12 Months Ended
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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 |

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