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Significant Accounting Polices (Details) - USD ($) $ in Thousands |  | 3 Months Ended | 9 Months Ended |  |
--- | --- | --- | --- | --- | ---
Jul. 01, 2018 | Sep. 30, 2018 | Mar. 31, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016
Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Loss expected to be reclassified to interest expense in next 12 months |  |  |  |  | $ 7,000 |  |  |
Increase to hedged deposit balances |  | $ 33,000 |  |  | 33,000 |  | $ 20,000 |
Cumulative effect of adoption of accounting principle |  |  |  |  |  |  |  | $ 165
(Losses) gains on derivatives and hedging activities, net |  | (4,949) |  | $ 1,661 | (6,325) | $ (7,326) |  |
Retained Earnings |  |  |  |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of adoption of accounting principle |  |  |  |  |  |  |  | $ (264)
Reclassification resulting from the adoption of tax cuts and jobs act |  |  | $ 600 |  | (592) |  |  |
Accumulated Other Comprehensive Income |  |  |  |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Reclassification resulting from the adoption of tax cuts and jobs act |  |  | $ 600 |  | 592 |  |  |
Accounting Standards Update 2017-12 |  |  |  |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of adoption of accounting principle |  |  |  |  |  |  | 1,052 |
Accounting Standards Update 2017-12 | Retained Earnings |  |  |  |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of adoption of accounting principle |  |  |  |  |  |  | 782 |
Accounting Standards Update 2017-12 | Accumulated Other Comprehensive Income |  |  |  |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of adoption of accounting principle |  |  |  |  |  |  | $ 270 |
Fair Value Hedges | Accounting Standards Update 2017-12 |  |  |  |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Increase to hedged deposit balances | $ 2,000 |  |  |  |  |  |  |
(Losses) gains on derivatives and hedging activities, net | (3,000) |  |  |  |  |  |  |
Fair Value Hedges | Accounting Standards Update 2017-12 | Retained Earnings |  |  |  |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of adoption of accounting principle | $ 1,000 |  |  |  |  |  |  |
Cash Flow Hedges | Accounting Standards Update 2017-12 | Retained Earnings |  |  |  |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of adoption of accounting principle |  | (300) |  |  | (300) |  |  |
Cash Flow Hedges | Accounting Standards Update 2017-12 | Accumulated Other Comprehensive Income |  |  |  |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |
Cumulative effect of adoption of accounting principle |  | $ 300 |  |  | $ 300 |  |  |

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- Definition Amount of increase (decrease) in accumulated other comprehensive income (AOCI) for reclassification to retained earnings of tax effect from remeasurement of deferred tax pursuant to Tax Cuts and Jobs Act of 2017. + References No definition available. + Details
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