Consolidated Statements of Changes in Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Common Stock and Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance (shares) at Dec. 31, 2016		381.1
Stockholders' equity, Beginning balance at Dec. 31, 2016	$ 4,962.5		$ 8,281.6	$ (37.3)	$ (3,281.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	306.2				306.2
Other comprehensive income (loss), net	31.9			31.9
Issuance of common stock (in shares)		10.7
Issuance of common stock	64.5		64.5
Repurchase and retirement of common stock (in shares)		(26.3)
Repurchase and retirement of common stock	(725.8)		(354.6)		(371.2)
Share-based compensation expense	188.2		188.2
Payment of cash dividends	(150.4)		(150.4)
Ending balance (shares) at Dec. 31, 2017		365.5
Stockholders' equity, Ending balance at Dec. 31, 2017	4,680.9		8,042.1	(5.4)	(3,355.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	566.9				566.9
Other comprehensive income (loss), net	(18.5)			(18.5)
Issuance of common stock (in shares)		10.4
Issuance of common stock	56.9		56.9
Repurchase and retirement of common stock (in shares)		(29.5)
Repurchase and retirement of common stock	(756.6)		(395.1)		(361.5)
Share-based compensation expense	218.2		218.2
Payment of cash dividends	(249.3)		(249.3)
Reclassification of tax effects upon adoption of ASU 2018-02 (Topic 220), net	$ 0.0			5.7	(5.7)
Ending balance (shares) at Dec. 31, 2018	346.4	346.4
Stockholders' equity, Ending balance at Dec. 31, 2018	$ 4,823.2		7,672.8	(18.2)	(2,831.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	345.0				345.0
Other comprehensive income (loss), net	(0.3)			(0.3)
Issuance of common stock (in shares)		9.8
Issuance of common stock	55.6		55.6
Common stock assumed upon business combination	4.6		4.6
Repurchase and retirement of common stock (in shares)		(20.3)
Repurchase and retirement of common stock	(514.9)		(264.6)		(250.3)
Share-based compensation expense	202.2		202.2
Payment of cash dividends	(260.1)		(260.1)
Purchase of forward contract under accelerated share repurchase program (ASR)	$ (40.0)		(40.0)
Ending balance (shares) at Dec. 31, 2019	335.9	335.9
Stockholders' equity, Ending balance at Dec. 31, 2019	$ 4,610.6		$ 7,370.5	$ (18.5)	$ (2,741.4)