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Investments - Narrative (Details) - USD ($)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]      
Proceeds from sales of marketable securities $ 0 $ 14,500,000 $ 3,000,000
Realized gains or losses from equity securities 0 0  
Reclassified from accumulated OCI 0 $ 0 $ 0
Unrealized gains or losses on equity securities 0    
Total equity investments $ 400,000