Consolidated Statement of Changes in Stockholders' Equity - USD ($) $ in Millions	Total	$0.001 Par Value Common Stock	Additional Paid-In Capital	Treasury Stock	Accumulated Other Comprehensive Loss	Retained Earnings
Beginning balance (in shares) at Dec. 31, 2016		41,000,000.0		400,000
Beginning balance at Dec. 31, 2016	$ 596.2	$ 0.0	$ 352.4	$ (6.4)	$ (4.3)	$ 254.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee equity plans activity (in shares)		1,100,000
Employee equity plans activity	28.0		28.0
Shares issued to extinguish convertible notes (in shares)		8,500,000
Shares issued to extinguish convertible notes	238.0	$ 0.1	237.9
Treasury stock (in shares)				(800,000)
Treasury stock	(33.1)			$ (33.1)
Net income	82.6					82.6
Other comprehensive income (loss)	0.6				0.6
Ending balance (in shares) at Dec. 31, 2017		50,600,000		1,200,000
Ending balance at Dec. 31, 2017	912.3	$ 0.1	618.3	$ (39.5)	(3.7)	337.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee equity plans activity (in shares)		1,100,000
Employee equity plans activity	32.6		32.6
Issuance of common stock in acquisitions (in shares)		700,000
Issuance of common stock in acquisition	37.7		37.7
Treasury stock	(0.1)			$ (0.1)
Net income	62.7					62.7
Other comprehensive income (loss)	$ (1.8)				(1.8)
Ending balance (in shares) at Dec. 31, 2018	52,400,000.0	52,400,000		1,200,000
Ending balance at Dec. 31, 2018	$ 1,010.9	$ 0.1	688.6	$ (39.6)	(5.5)	367.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee equity plans activity (in shares)		600,000
Employee equity plans activity	27.5		27.5
Net income	54.5					54.5
Other comprehensive income (loss)	$ (4.4)				(4.4)
Ending balance (in shares) at Dec. 31, 2019	52,900,000.0	53,000,000.0		1,200,000
Ending balance at Dec. 31, 2019	$ 1,088.5	$ 0.1	$ 716.1	$ (39.6)	$ (9.9)	$ 421.8