CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment	Additional Paid-in Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Cumulative Effect, Period of Adoption, Adjustment	Treasury Stock	Class A Stock	Common Stock
Beginning Balance (in shares) at Dec. 31, 2017								(3.8)	1.9	109.5
Beginning Balance at Dec. 31, 2017	$ 6,144.1	$ (143.4)	$ 3,512.9	$ 2,946.7	$ (136.8)	$ 0.6	$ (6.6)	$ (316.2)		$ 0.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock for equity awards granted under long-term incentive plans (in shares)										2.0
Issuance of Common Stock for equity awards granted under long-term incentive plans	114.2		114.2
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations (in shares)										(0.5)
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations	(187.2)		(187.2)
Issuance/distribution of Common Stock for 401(k) Savings Plan (in shares)										0.1
Issuance/distribution of Common Stock for 401(k) Savings Plan	26.9		26.9
Repurchases of Common Stock (in shares)								(0.2)
Repurchases of Common Stock	(80.2)							$ (80.2)
Stock-based compensation charges	444.8		444.8
Net income	2,444.4			2,444.4
Other comprehensive income (loss), net of tax	(6.3)					(6.3)
Ending Balance (in shares) at Dec. 31, 2018								(4.0)	1.9	111.1
Ending Balance at Dec. 31, 2018	8,757.3	$ 9.7	3,911.6	5,254.3	$ 9.7	(12.3)		$ (396.4)		$ 0.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock for equity awards granted under long-term incentive plans (in shares)										2.6
Issuance of Common Stock for equity awards granted under long-term incentive plans	213.2		213.2
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations (in shares)										(0.5)
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations	(188.0)		(188.0)
Issuance/distribution of Common Stock for 401(k) Savings Plan (in shares)								0.1
Issuance/distribution of Common Stock for 401(k) Savings Plan	38.1		24.9					$ 13.2
Repurchases of Common Stock (in shares)								(1.0)
Repurchases of Common Stock	(356.7)							$ (356.7)
Conversion of Class A Stock to Common Stock (in shares)									(0.1)	0.1
Conversion of Class A Stock to Common Stock	0.0
Stock-based compensation charges	466.9		466.9
Net income	2,115.8			2,115.8
Other comprehensive income (loss), net of tax	33.4					33.4
Ending Balance (in shares) at Dec. 31, 2019								(4.9)	1.8	113.3
Ending Balance at Dec. 31, 2019	11,089.7		4,428.6	7,379.8		21.1		$ (739.9)		$ 0.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock for equity awards granted under long-term incentive plans (in shares)										9.6
Issuance of Common Stock for equity awards granted under long-term incentive plans	2,576.4		2,576.4
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations (in shares)										(1.4)
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations	(768.9)		(768.9)
Issuance/distribution of Common Stock for 401(k) Savings Plan (in shares)								0.1
Issuance/distribution of Common Stock for 401(k) Savings Plan	44.7		37.2					$ 7.5
Repurchases of Common Stock (in shares)								(11.6)
Repurchases of Common Stock	(5,880.9)							$ (5,880.9)
Stock-based compensation charges	442.9		442.9
Net income	3,513.2			3,513.2
Other comprehensive income (loss), net of tax	8.2					8.2
Ending Balance (in shares) at Dec. 31, 2020								(16.4)	1.8	121.5
Ending Balance at Dec. 31, 2020	$ 11,025.3		$ 6,716.2	$ 10,893.0		$ 29.3		$ (6,613.3)		$ 0.1