CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Millions	Total	Redeemable Noncontrolling Interest	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance, beginning of period at Dec. 29, 2019		$ 15.0
Redeemable Noncontrolling Interest
Net income (loss)		(0.1)
Balance, end of period at Sep. 27, 2020		14.9
Balance, beginning of period (in shares) at Dec. 29, 2019			106,600,000
Balance, beginning of period at Dec. 29, 2019	$ 574.1		$ 0.0	$ 1,286.5	$ (0.4)	$ (712.0)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation	14.5			14.5
Issuance of common stock for employee stock purchase plan and stock options (in shares)			400,000
Issuance of common stock for employee stock purchase plan and stock options	5.3			5.3
Restricted stock issued and related taxes (in shares)			200,000
Restricted stock issued and related taxes	(1.3)			(1.3)
Issuance of common stock for cash (in shares)			15,500,000
Issuance of common stock for cash	240.4			240.4
Net income (loss)	1.5					1.5
Other comprehensive income (loss), net of tax	0.8				0.8
Balance, end of period (in shares) at Sep. 27, 2020			122,700,000
Balance, end of period at Sep. 27, 2020	835.3		$ 0.0	1,545.4	0.4	(710.5)
Balance, beginning of period at Jun. 28, 2020		14.9
Redeemable Noncontrolling Interest
Net income (loss)		0.0
Balance, end of period at Sep. 27, 2020		14.9
Balance, beginning of period (in shares) at Jun. 28, 2020			122,500,000
Balance, beginning of period at Jun. 28, 2020	824.5		$ 0.0	1,537.9	(0.5)	(712.9)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation	5.0			5.0
Issuance of common stock for employee stock purchase plan and stock options (in shares)			200,000
Issuance of common stock for employee stock purchase plan and stock options	2.7			2.7
Restricted stock issued and related taxes	(0.1)			(0.1)
Issuance of common stock for cash	(0.1)			(0.1)
Net income (loss)	2.4					2.4
Other comprehensive income (loss), net of tax	0.9				0.9
Balance, end of period (in shares) at Sep. 27, 2020			122,700,000
Balance, end of period at Sep. 27, 2020	$ 835.3		$ 0.0	1,545.4	0.4	(710.5)
Balance, beginning of period at Dec. 27, 2020		14.8
Redeemable Noncontrolling Interest
Net income (loss)		0.3
Balance, end of period at Sep. 26, 2021		15.1
Balance, beginning of period (in shares) at Dec. 27, 2020	123,047,147		123,000,000.0
Balance, beginning of period at Dec. 27, 2020	$ 925.3		$ 0.0	1,556.3	1.4	(632.4)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation	19.2			19.2
Issuance of common stock for employee stock purchase plan and stock options (in shares)			400,000
Issuance of common stock for employee stock purchase plan and stock options	5.9			5.9
Restricted stock issued and related taxes (in shares)			600,000
Restricted stock issued and related taxes	(9.1)			(9.1)
Net income (loss)	0.6					0.6
Other comprehensive income (loss), net of tax	$ (0.1)				(0.1)
Balance, end of period (in shares) at Sep. 26, 2021	123,986,345		124,000,000.0
Balance, end of period at Sep. 26, 2021	$ 941.8		$ 0.0	1,572.3	1.3	(631.8)
Balance, beginning of period at Jun. 27, 2021		14.6
Redeemable Noncontrolling Interest
Net income (loss)		0.5
Balance, end of period at Sep. 26, 2021		$ 15.1
Balance, beginning of period (in shares) at Jun. 27, 2021			123,800,000
Balance, beginning of period at Jun. 27, 2021	935.9		$ 0.0	1,563.1	2.2	(629.4)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation	6.4			6.4
Issuance of common stock for employee stock purchase plan and stock options (in shares)			200,000
Issuance of common stock for employee stock purchase plan and stock options	3.4			3.4
Restricted stock issued and related taxes	(0.6)			(0.6)
Net income (loss)	(2.4)					(2.4)
Other comprehensive income (loss), net of tax	$ (0.9)				(0.9)
Balance, end of period (in shares) at Sep. 26, 2021	123,986,345		124,000,000.0
Balance, end of period at Sep. 26, 2021	$ 941.8		$ 0.0	$ 1,572.3	$ 1.3	$ (631.8)