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Debt and Credit Facility, Narrative (Details) - USD ($) |  | 3 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Dec. 18, 2019 | Mar. 31, 2020 | Mar. 31, 2019 | Dec. 31, 2019 | Nov. 26, 2019 | May 15, 2016
Debt Instrument |  |  |  |  |  |
Interest expense capitalized |  | $ 300,000 | $ 500,000 |  |  |
Senior Notes Due 2028 | Senior Notes |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |
Debt principal amount |  |  |  |  | $ 500,000,000.0 |
Debt instrument contractual rate (percent) |  |  |  |  | 4.625% |
Debt issuance, percentage of principal amount |  |  |  |  | 100.00% |
Unamortized debt issuance cost |  | 7,200,000 |  |  |  |
Interest expense |  | $ 6,000,000.0 |  |  |  |
Effective interest rate (percent) |  | 4.80% |  |  |  |
Fair value of outstanding debt |  | $ 438,100,000 |  | $ 513,500,000 |  |
Senior Notes Due 2024 | Senior Notes |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |
Debt principal amount |  |  |  |  |  | $ 375,000,000.0
Debt instrument contractual rate (percent) |  |  |  |  |  | 5.875%
Debt issuance, percentage of principal amount |  |  |  |  |  | 100.00%
Interest expense |  |  | $ 5,700,000 |  |  |
Effective interest rate (percent) |  |  | 6.10% |  |  |
On or after May 15, 2019 | Senior Notes Due 2024 | Senior Notes |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |
Debt Instrument, Redemption Price, Percentage | 104.406% |  |  |  |  |

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- Definition Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6036836-161870 Reference 2: 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=114775744&loc=d3e28551-108399 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(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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