Condensed Consolidated Statements 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
Balance (in shares) at Dec. 31, 2018		52,400,000		1,200,000
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)		300,000
Employee equity plans activity	13.1		13.2	$ (0.1)
Net income (loss)	(35.6)					(35.6)
Other comprehensive income	0.5				0.5
Balance (in shares) at Jun. 30, 2019		52,700,000		1,200,000
Balance at Jun. 30, 2019	988.9	$ 0.1	701.8	$ (39.7)	(5.0)	331.7
Balance (in shares) at Mar. 31, 2019		52,600,000		1,200,000
Balance at Mar. 31, 2019	987.3	$ 0.1	690.1	$ (39.6)	(4.5)	341.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee equity plans activity (in shares)		100,000
Employee equity plans activity	11.6		11.7	$ (0.1)
Net income (loss)	(9.5)					(9.5)
Other comprehensive income	(0.5)				(0.5)
Balance (in shares) at Jun. 30, 2019		52,700,000		1,200,000
Balance at Jun. 30, 2019	$ 988.9	$ 0.1	701.8	$ (39.7)	(5.0)	331.7
Balance (in shares) at Dec. 31, 2019	53,000,000	53,000,000.0		1,200,000
Balance at Dec. 31, 2019	$ 1,088.5	$ 0.1	716.1	$ (39.6)	(9.9)	421.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee equity plans activity (in shares)		1,100,000
Employee equity plans activity	42.4		42.4	$ 0.0
Net income (loss)	80.2					80.2
Other comprehensive income	$ (12.3)				(12.3)
Balance (in shares) at Jun. 30, 2020	54,100,000	54,100,000		1,200,000
Balance at Jun. 30, 2020	$ 1,198.8	$ 0.1	758.5	$ (39.6)	(22.2)	502.0
Balance (in shares) at Mar. 31, 2020		53,500,000		1,200,000
Balance at Mar. 31, 2020	1,074.8	$ 0.1	726.2	$ (39.6)	(21.2)	409.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee equity plans activity (in shares)		600,000
Employee equity plans activity	32.3		32.3	$ 0.0
Net income (loss)	92.7					92.7
Other comprehensive income	$ (1.0)				(1.0)
Balance (in shares) at Jun. 30, 2020	54,100,000	54,100,000		1,200,000
Balance at Jun. 30, 2020	$ 1,198.8	$ 0.1	$ 758.5	$ (39.6)	$ (22.2)	$ 502.0