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Long-Term Debt - Narrative (Details) - USD ($)
$ in Thousands
Mar. 31, 2021
Dec. 31, 2020
Debt Instrument [Line Items]    
Estimated fair value of long-term debt $ 994,100 $ 1,010,000
Long-term debt, gross 1,000,000 $ 1,000,000
2017 Revolving Credit Facility | Revolving Credit Facility    
Debt Instrument [Line Items]    
Available borrowing capacity $ 500,000