CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - 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)	Treasury Stock	Class A Stock	Common Stock
Beginning Balance (in shares) at Dec. 31, 2018							(4.0)	1.9	111.1
Beginning Balance at Dec. 31, 2018	$ 8,757.3	$ 9.7	$ 3,911.6	$ 5,254.3	$ 9.7	$ (12.3)	$ (396.4)	$ 0.0	$ 0.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock for equity awards granted under long-term incentive plans (in shares)									0.6
Issuance of Common Stock for equity awards granted under long-term incentive plans	140.9		140.9
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations	(10.7)		(10.7)
Issuance/distribution of Common Stock for 401(k) Savings Plan	10.5		4.3				$ 6.2
Issuance/distribution of Common Stock in connection with 401(k) Savings Plan (in shares)							0.1
Repurchases of Common Stock (in shares)							(0.1)
Repurchases of Common Stock	(54.0)						$ (54.0)
Stock-based compensation charges	114.8		114.8
Net income	461.1			461.1
Other comprehensive income (loss), net of tax	15.1					15.1
Ending Balance (in shares) at Mar. 31, 2019							(4.0)	1.9	111.7
Ending Balance at Mar. 31, 2019	9,444.7		4,160.9	5,725.1		2.8	$ (444.2)	$ 0.0	$ 0.1
Beginning Balance (in shares) at Dec. 31, 2018							(4.0)	1.9	111.1
Beginning Balance at Dec. 31, 2018	8,757.3	$ 9.7	3,911.6	5,254.3	$ 9.7	(12.3)	$ (396.4)	$ 0.0	$ 0.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	654.2
Ending Balance (in shares) at Jun. 30, 2019							(4.0)	1.9	111.9
Ending Balance at Jun. 30, 2019	9,755.9		4,263.6	5,918.2		15.8	$ (441.8)	$ 0.0	$ 0.1
Beginning Balance (in shares) at Mar. 31, 2019							(4.0)	1.9	111.7
Beginning Balance at Mar. 31, 2019	9,444.7		4,160.9	5,725.1		2.8	$ (444.2)	$ 0.0	$ 0.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock for equity awards granted under long-term incentive plans (in shares)									0.3
Issuance of Common Stock for equity awards granted under long-term incentive plans	13.9		13.9
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations (in shares)									(0.1)
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations	(29.7)		(29.7)
Issuance/distribution of Common Stock for 401(k) Savings Plan	11.7		9.3				$ 2.4
Stock-based compensation charges	109.2		109.2
Net income	193.1			193.1
Other comprehensive income (loss), net of tax	13.0					13.0
Ending Balance (in shares) at Jun. 30, 2019							(4.0)	1.9	111.9
Ending Balance at Jun. 30, 2019	9,755.9		4,263.6	5,918.2		15.8	$ (441.8)	$ 0.0	$ 0.1
Beginning Balance (in shares) at Dec. 31, 2019							(4.9)	1.8	113.3
Beginning Balance at Dec. 31, 2019	11,089.7		4,428.6	7,379.8		21.1	$ (739.9)	$ 0.0	$ 0.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock for equity awards granted under long-term incentive plans (in shares)									3.1
Issuance of Common Stock for equity awards granted under long-term incentive plans	817.4		817.4
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations (in shares)									(0.4)
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations	(155.1)		(155.1)
Issuance/distribution of Common Stock for 401(k) Savings Plan	14.6		12.5				$ 2.1
Issuance/distribution of Common Stock in connection with 401(k) Savings Plan (in shares)							0.0
Repurchases of Common Stock (in shares)							(0.8)
Repurchases of Common Stock	(336.0)						$ (336.0)
Stock-based compensation charges	108.0		108.0
Net income	624.6			624.6
Other comprehensive income (loss), net of tax	(30.2)					(30.2)
Ending Balance (in shares) at Mar. 31, 2020							(5.7)	1.8	116.0
Ending Balance at Mar. 31, 2020	12,133.0		5,211.4	8,004.4		(9.1)	$ (1,073.8)	$ 0.0	$ 0.1
Beginning Balance (in shares) at Dec. 31, 2019							(4.9)	1.8	113.3
Beginning Balance at Dec. 31, 2019	11,089.7		4,428.6	7,379.8		21.1	$ (739.9)	$ 0.0	$ 0.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,521.9
Ending Balance (in shares) at Jun. 30, 2020							(15.6)	1.8	119.8
Ending Balance at Jun. 30, 2020	9,057.4		6,263.0	8,901.7		35.5	$ (6,142.9)	$ 0.0	$ 0.1
Beginning Balance (in shares) at Mar. 31, 2020							(5.7)	1.8	116.0
Beginning Balance at Mar. 31, 2020	12,133.0		5,211.4	8,004.4		(9.1)	$ (1,073.8)	$ 0.0	$ 0.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock for equity awards granted under long-term incentive plans (in shares)									4.4
Issuance of Common Stock for equity awards granted under long-term incentive plans	1,355.5		1,355.5
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations (in shares)									(0.6)
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations	(416.5)		(416.5)
Issuance/distribution of Common Stock for 401(k) Savings Plan	10.1		7.4				$ 2.7
Issuance/distribution of Common Stock in connection with 401(k) Savings Plan (in shares)							0.0
Repurchases of Common Stock (in shares)							(9.9)
Repurchases of Common Stock	(5,071.8)						$ (5,071.8)
Stock-based compensation charges	105.2		105.2
Net income	897.3			897.3
Other comprehensive income (loss), net of tax	44.6					44.6
Ending Balance (in shares) at Jun. 30, 2020							(15.6)	1.8	119.8
Ending Balance at Jun. 30, 2020	$ 9,057.4		$ 6,263.0	$ 8,901.7		$ 35.5	$ (6,142.9)	$ 0.0	$ 0.1