Net Income per Share (Narrative) (Details) - USD ($)	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from EPS (in shares)	300,000	700,000
Amount authorized under stock repurchase program	$ 1,500,000,000
Available for repurchase under the stock repurchase program	$ 135,300,000
Class A Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of shares repurchased (in shares)	0
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from EPS (in shares)	500,000	1,100,000