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Financing Agreements (Convertible Senior Notes) (Details) |  | 12 Months Ended
--- | --- | ---
Jun. 03, 2019 USD ($) $ / shares | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($)
Debt Instrument [Line Items] |  |  |  |
Proceeds from issuance of Convertible Senior Notes |  | $ 0 | $ 223,311,000 | $ 0
Convertible Debt |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Proceeds from issuance of Convertible Senior Notes | $ 230,000,000.0 |  |  |
Proceed from debt net of offering expenses and underwriting discount | $ 223,300,000 |  |  |
Stated interest rate | 6.25% |  |  |
Conversion ratio | 125.7387 |  |  |
Face amount | $ 1,000 |  |  |
Conversion price (in dollars per share) | $ / shares | $ 7.95 |  |  |
Effective interest rate | 6.94% |  |  |
Additional Convertible Senior Notes |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Proceeds from issuance of Convertible Senior Notes | $ 30,000,000.0 |  |  |

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