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Financing Agreements (Narrative) (Details) - USD ($) | 3 Months Ended |
--- | --- | ---
Mar. 31, 2021 | Jun. 30, 2020 | Dec. 31, 2020
Financing Agreements [Line Items] |  |  |
Agreement amount | $ 3,998,346,000 |  | $ 4,339,479,000
Financial instruments | 3,995,982,000 |  | 4,336,976,000
Financing Agreement |  |  |
Financing Agreements [Line Items] |  |  |
Cash pledged as collateral | 5,200,000 |  | 7,200,000
Senior Secured Credit Agreement |  |  |
Financing Agreements [Line Items] |  |  |
Agreement amount |  | $ 500,000,000 |
Financing agreements with mark-to-market collateral provisions |  |  |
Financing Agreements [Line Items] |  |  |
Agreement amount | 1,180,287,000 |  | 1,338,077,000
Financial instruments | 1,180,287,000 | $ 1,650,000,000 | $ 1,338,077,000
Non Mark to Market Financing Facilities [Member] |  |  |
Financing Agreements [Line Items] |  |  |
Financial instruments | $ 837,800,000 |  |
Debt instrument term | 2 years | 2 years |
Debt instrument, term, extension |  | 3 years |
Non Mark to Market Financing Facilities on Rehabilitation Loans |  |  |
Financing Agreements [Line Items] |  |  |
Long-term debt, term |  | 2 years |
Debt outstanding | $ 203,500,000 |  |
Minimum | Financing agreements with mark-to-market collateral provisions |  |  |
Financing Agreements [Line Items] |  |  |
Debt instrument term | 1 month |  |
Maximum | Financing agreements with mark-to-market collateral provisions |  |  |
Financing Agreements [Line Items] |  |  |
Debt instrument term | 3 months |  |

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- Definition Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details
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