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Significant Accounting Policies Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands | Sep. 30, 2020 | Jan. 01, 2020 | Dec. 31, 2019 | Jan. 01, 2019 | Dec. 31, 2018
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New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |
Cumulative effect of accounting change |  |  | $ (29,252) |  | $ (14,672)
Debt Securities, Threshold Period Past Due | 90 days |  |  |  |
Operating Lease, Right-of-Use Asset | $ 298,600 |  | 297,700 | $ 170,500 |
Operating Lease, Liability | $ 328,900 |  | 323,700 | 174,400 |
Retained Earnings [Member] |  |  |  |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |  |  |
Cumulative effect of accounting change |  | $ (29,300) | $ (29,252) | $ (14,700) | $ (14,672)

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- Definition New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity, Net of Tax + References No definition available. + Details
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- Definition Threshold period for when investment in debt security measured at amortized cost (held-to-maturity) is considered past due, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Excludes threshold period past due to write off as uncollectible. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919253-210447 + Details
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- Definition Present value of lessee's discounted obligation for lease payments from operating lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918627-209977 + Details
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- Definition Amount of lessee's right to use underlying asset under operating lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918627-209977 + Details
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