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Interest Expense (Details) - USD ($) |  | 1 Months Ended | 3 Months Ended | 6 Months Ended | 9 Months Ended
--- | --- | --- | --- | --- | ---
Dec. 22, 2020 | Feb. 28, 2021 | Dec. 31, 2020 | Sep. 30, 2021 | Sep. 30, 2020 | Jun. 30, 2021 | Sep. 30, 2021 | Sep. 30, 2020
Interest and Debt Expense [Abstract] |  |  |  |  |  |  |  |
Interest Expense, Debt |  |  |  | $ 13,526,000 | $ 20,893,000 |  | $ 44,476,000 | $ 64,285,000
Accretion of fair value adjustment on Senior Notes |  |  |  | 815,000 | 549,000 |  | 2,658,000 | 1,647,000
Amortization of Debt Issuance Costs |  |  |  | 1,707,000 | 1,032,000 |  | 7,075,000 | 3,094,000
Interest Expense, Total |  |  |  | 16,048,000 | 22,474,000 |  | 54,209,000 | 69,026,000
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Subordinated Borrowing, Interest Rate | 4.625% |  |  |  |  |  |  |
Repayments of Secured Debt |  |  |  |  |  |  | 300,000,000 | 249,214,000
Amortization of Debt Issuance Costs |  |  |  | 1,707,000 | $ 1,032,000 |  | 7,075,000 | $ 3,094,000
Term Loan Facility |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Payments of Debt Restructuring Costs |  |  |  |  |  |  | $ 1,600,000 |
2018 Credit Agreement |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Line of Credit Facility, Interest Rate During Period |  |  |  |  |  | 4.50% | 3.50% |
2018 Credit Agreement | Term Loan Facility |  |  |  |  |  |  |  |
Interest and Debt Expense [Abstract] |  |  |  |  |  |  |  |
Amortization of Debt Issuance Costs |  | $ 900,000 |  | 500,000 |  |  | $ 1,800,000 |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Repayments of Secured Debt |  |  | $ 500,000,000 | 100,000,000 |  |  | 300,000,000 |
Accretion Expense |  |  |  | 900,000 |  |  | 2,900,000 |
Amortization of Debt Issuance Costs |  | $ 900,000 |  | $ 500,000 |  |  | $ 1,800,000 |

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- Definition Amount recognized for the passage of time, typically for liabilities, that have been discounted to their net present values. Excludes accretion associated with asset retirement obligations. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 420 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b)(2) -URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6392676&loc=d3e7480-110848 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 420 -SubTopic 10 -Section 35 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6394232&loc=d3e17558-110866 + Details
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