CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions	Total	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Class A Stock	Common Stock
Beginning Balance (in shares) at Dec. 31, 2016					(3.8)	1.9	107.9
Beginning Balance at Dec. 31, 2016	$ 4,449.3	$ 3,030.0	$ 1,748.2	$ (12.8)	$ (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)							2.4
Issuance of Common Stock for equity awards granted under long-term incentive plans	240.6	240.6
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations (in shares)							(0.8)
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations	(301.7)	(301.7)
Issuance/distribution of Common Stock for 401(k) Savings Plan	19.4	19.4
Stock-based compensation charges	524.6	524.6
Net income	1,198.5		1,198.5
Other comprehensive income (loss), net of tax	13.4			13.4
Ending Balance (in shares) at Dec. 31, 2017					(3.8)	1.9	109.5
Ending Balance at Dec. 31, 2017	6,144.1	3,512.9	2,946.7	0.6	$ (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
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)
Repurchases of Common Stock (in shares)					(0.2)
Repurchases of Common Stock	(80.2)				$ (80.2)
Ending Balance (in shares) at Dec. 31, 2018					(4.0)	1.9	111.1
Ending Balance at Dec. 31, 2018	8,757.3	3,911.6	5,254.3	(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
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
Repurchases of Common Stock (in shares)					(1.0)
Repurchases of Common Stock	(356.7)				$ (356.7)
Conversion of Class A Stock to Common Stock						0.1	0.1
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