Condensed 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	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjustment Accumulated Deficit
Balance (in shares) at Dec. 31, 2018		346.4
Balance at Dec. 31, 2018	$ 4,823.2		$ 7,672.8	$ (18.2)	$ (2,831.4)
Balance (Accounting Standards Update 2017-12) at Dec. 31, 2018						$ 0.1	$ 0.1
Balance (Accounting Standards Update 2016-02) at Dec. 31, 2018						$ (4.8)	$ (4.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	77.3				77.3
Other comprehensive income, net	6.9			6.9
Issuance of common stock (in shares)		6.8
Issuance of common stock	29.7		29.7
Common stock assumed upon business combination	4.7		4.7
Repurchase and retirement of common stock (in shares)		(8.7)
Repurchase and retirement of common stock	(243.8)		(113.9)		(129.9)
Purchase of forward contract under accelerated share repurchase program (ASR)	(60.0)		(60.0)
Share-based compensation expense	89.6		89.6
Payments of cash dividends	(131.7)		(131.7)
Balance (in shares) at Jun. 30, 2019		344.5
Balance at Jun. 30, 2019	4,591.2		7,491.2	(11.3)	(2,888.7)
Balance (in shares) at Mar. 31, 2019		352.0
Balance at Mar. 31, 2019	4,851.2		7,668.6	(10.9)	(2,806.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	46.2				46.2
Other comprehensive income, net	(0.4)			(0.4)
Issuance of common stock (in shares)		1.1
Issuance of common stock	0.2		0.2
Common stock assumed upon business combination	4.7		4.7
Repurchase and retirement of common stock (in shares)		(8.6)
Repurchase and retirement of common stock	(240.9)		(112.5)		(128.4)
Purchase of forward contract under accelerated share repurchase program (ASR)	(60.0)		(60.0)
Share-based compensation expense	55.7		55.7
Payments of cash dividends	(65.5)		(65.5)
Balance (in shares) at Jun. 30, 2019		344.5
Balance at Jun. 30, 2019	4,591.2		7,491.2	(11.3)	(2,888.7)
Balance (in shares) at Dec. 31, 2019		335.9
Balance at Dec. 31, 2019	4,610.6		7,370.5	(18.5)	(2,741.4)
Balance (in shares) at Mar. 31, 2020		331.0
Balance at Mar. 31, 2020	4,390.7		7,281.3	(59.2)	(2,831.4)
Balance (in shares) at Dec. 31, 2019		335.9
Balance at Dec. 31, 2019	4,610.6		7,370.5	(18.5)	(2,741.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	81.6				81.6
Other comprehensive income, net	(4.4)			(4.4)
Issuance of common stock (in shares)		6.4
Issuance of common stock	27.6		27.6
Repurchase and retirement of common stock (in shares)		(10.6)
Repurchase and retirement of common stock	(245.3)		(136.6)		(108.7)
Purchase of forward contract under accelerated share repurchase program (ASR)	40.0		40.0
Share-based compensation expense	86.0		86.0
Payments of cash dividends	(131.8)		(131.8)
Balance (in shares) at Jun. 30, 2020		331.7
Balance at Jun. 30, 2020	4,464.3		7,255.7	(22.9)	(2,768.5)
Balance (in shares) at Mar. 31, 2020		331.0
Balance at Mar. 31, 2020	4,390.7		7,281.3	(59.2)	(2,831.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	61.2				61.2
Other comprehensive income, net	36.3			36.3
Issuance of common stock (in shares)		0.8
Issuance of common stock	0.5		0.5
Repurchase and retirement of common stock (in shares)		(0.1)
Repurchase and retirement of common stock	(2.1)		(3.8)		1.7
Share-based compensation expense	44.0		44.0
Payments of cash dividends	(66.3)		(66.3)
Balance (in shares) at Jun. 30, 2020		331.7
Balance at Jun. 30, 2020	$ 4,464.3		$ 7,255.7	$ (22.9)	$ (2,768.5)