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Stockholders' Equity - Summary of Share Repurchases (Details) - Class A - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended 59 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2020
Equity, Class of Treasury Stock [Line Items]        
Shares repurchased pursuant to repurchase authorizations 563,953 0 2,112,370 3,719,048
Total purchase price (in millions) $ 46.1 $ 0.0 $ 179.0  
Average purchase price per share (in dollars per share) $ 81.71 $ 0 $ 84.72 $ 84.02
Restricted Stock Units (RSUs)        
Equity, Class of Treasury Stock [Line Items]        
Shares repurchased in association with tax withholdings on the vesting of RSUs 30,620 40,356 30,119