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
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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	31.1				31.1
Other comprehensive loss, net	7.3			7.3
Issuance of common stock (in shares)		5.7
Issuance of common stock	29.5		29.5
Repurchase and retirement of common stock (in shares)		(0.1)
Repurchase and retirement of common stock	(2.9)		(1.4)		(1.5)
Share-based compensation expense	33.9		33.9
Payments of cash dividends	(66.2)		(66.2)
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)
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	20.4				20.4
Other comprehensive loss, net	(40.7)			(40.7)
Issuance of common stock (in shares)		5.6
Issuance of common stock	27.1		27.1
Repurchase and retirement of common stock (in shares)		(10.5)
Repurchase and retirement of common stock	(243.2)		(132.8)		(110.4)
Purchase of forward contract under accelerated share repurchase program (ASR)	40.0		40.0
Share-based compensation expense	42.0		42.0
Payments of cash dividends	(65.5)		(65.5)
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)