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Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020
AOCI Attributable to Parent, Net of Tax |  |  |  |
Balance, beginning | $ 2,353,955 | $ 2,203,715 | $ 2,307,041 | $ 1,960,733
Other comprehensive income (loss) before reclassifications |  |  | (63,109) | 91,630
Reclassification adjustments for gains included in net income (loss) |  |  |  | (758)
Total other comprehensive (loss) income, net of tax | (12,783) | 1,189 | (65,431) | 90,872
Balance, ending | 2,387,616 | 2,255,089 | 2,387,616 | 2,255,089
Gains (Losses) on Available-For-Sale and Transferred Debt Securities |  |  |  |
AOCI Attributable to Parent, Net of Tax |  |  |  |
Balance, beginning |  |  | 143,443 | 40,226
Other comprehensive income (loss) before reclassifications |  |  | (63,468) | 92,027
Reclassification adjustments for gains included in net income (loss) |  |  |  | (758)
Total other comprehensive (loss) income, net of tax |  |  | (65,790) | 91,269
Balance, ending | 77,653 | 131,495 | 77,653 | 131,495
(Losses) Gains on Derivatives Used for Cash Flow Hedges |  |  |  |
AOCI Attributable to Parent, Net of Tax |  |  |  |
Balance, beginning |  |  | (353) | 0
Other comprehensive income (loss) before reclassifications |  |  | 359 | (397)
Reclassification adjustments for gains included in net income (loss) |  |  |  | 0
Total other comprehensive (loss) income, net of tax |  |  | 359 | (397)
Balance, ending | 6 | (397) | 6 | (397)
Reclassification adjustments for gains and transfers included in net income |  |  |  |
AOCI Attributable to Parent, Net of Tax |  |  |  |
Reclassification adjustments for gains included in net income (loss) |  |  | 650 |
Reclassification adjustments for amortization included in net income for transferred securities |  |  |  |
AOCI Attributable to Parent, Net of Tax |  |  |  |
Reclassification adjustments for gains included in net income (loss) |  |  | 1,672 |
Accumulated Other Compre- hensive Income (loss) |  |  |  |
AOCI Attributable to Parent, Net of Tax |  |  |  |
Balance, beginning | 90,442 | 129,909 | 143,090 | 40,226
Total other comprehensive (loss) income, net of tax | (12,783) | 1,189 | (65,431) | 90,872
Balance, ending | $ 77,659 | $ 131,098 | $ 77,659 | $ 131,098

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- Definition Amount after tax, before reclassification adjustments of other comprehensive income (loss). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=124431353&loc=SL124442411-227067 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 30 -Section 45 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118261656&loc=d3e32136-110900 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 30 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6450520&loc=d3e32583-110901 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=124509347&loc=SL7669686-108580 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 55 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=124507222&loc=d3e1436-108581 Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=124431353&loc=SL124442407-227067 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 30 -Section 45 -Paragraph 20 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118261656&loc=d3e32211-110900 + Details
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