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v3.21.1

Long-Term Debt (Narrative) (Details) |  | 3 Months Ended |
--- | --- | --- | ---
Jan. 24, 2019 USD ($) | Mar. 31, 2021 USD ($) debtCovenant | Dec. 31, 2020 USD ($)
Revolving Credit Facility | Senior Credit Agreement |  |  |
Debt Instrument [Line Items] |  |  |
Revolving credit facility, availability amount |  | $ 334,800,000 | $ 309,200,000
Standby Letters of Credit | Senior Credit Agreement |  |  |
Debt Instrument [Line Items] |  |  |
Letters of credit issued |  | $ 6,200,000 |
Line of Credit | 2019 Senior Credit Agreement |  |  |
Debt Instrument [Line Items] |  |  |
Current borrowing capacity | $ 400,000,000 |  |
Letters of credit issued | $ 700,000,000 |  |
Number of debt covenants | debtCovenant |  | 3 |
Line of Credit | 2019 Senior Credit Agreement | Minimum |  |  |
Debt Instrument [Line Items] |  |  |
Revolving credit facility, undrawn commitment fee | 0.15% |  |
Line of Credit | 2019 Senior Credit Agreement | Minimum | London Interbank Offered Rate (LIBOR) |  |  |
Debt Instrument [Line Items] |  |  |
Revolfing credit facility, interest rates margin | 1.125% |  |
Line of Credit | 2019 Senior Credit Agreement | Maximum |  |  |
Debt Instrument [Line Items] |  |  |
Revolving credit facility, undrawn commitment fee | 0.25% |  |
Line of Credit | 2019 Senior Credit Agreement | Maximum | London Interbank Offered Rate (LIBOR) |  |  |
Debt Instrument [Line Items] |  |  |
Revolfing credit facility, interest rates margin | 2.00% |  |
Medium-term Notes | 2019 Senior Credit Agreement |  |  |
Debt Instrument [Line Items] |  |  |
Debt instrument, issued value | $ 300,000,000 |  |

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- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400 + Details
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