Net Income per Share (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from EPS (in shares)	400,000	400,000
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	0
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from EPS (in shares)	500,000	1,300,000