Net Income per Share (Narrative) (Details) - USD ($)	6 Months Ended
	Jun. 30, 2021	Jun. 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	1,200,000