CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance, beginning of period (in shares) at Dec. 28, 2014		57,800,000
Balance, beginning of period at Dec. 28, 2014	$ 224.3	$ 0.0	$ 863.4	$ (1.7)	$ (637.4)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation	6.4		6.4
Issuance of common stock for employee stock purchase plan, options and warrants (in shares)		900,000
Issuance of common stock for employee stock purchase plan, options and warrants	4.0		4.0
Restricted stock issued and related taxes (in shares)		400,000
Restricted stock issued and related taxes	(0.6)		(0.6)
Net income (loss)	19.8				19.8
Other comprehensive income (loss), net of tax	0.3			0.3
Balance, end of period (in shares) at Dec. 27, 2015		59,100,000
Balance, end of period at Dec. 27, 2015	254.2	$ 0.0	873.2	(1.4)	(617.6)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation	5.1		5.1
Issuance of common stock for cash (in shares)		13,400,000
Issuance of common stock for cash	75.8		75.8
Issuance of common stock for employee stock purchase plan, options and warrants (in shares)		800,000
Issuance of common stock for employee stock purchase plan, options and warrants	2.6		2.6
Restricted stock issued and related taxes (in shares)		600,000
Restricted stock issued and related taxes	(0.5)		(0.5)
Net income (loss)	(60.5)				(60.5)
Other comprehensive income (loss), net of tax	$ (0.3)			(0.3)
Balance, end of period (in shares) at Dec. 25, 2016	73,945,533	73,900,000
Balance, end of period at Dec. 25, 2016	$ 276.4	$ 0.0	956.2	(1.7)	(678.1)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation	7.8		7.8
Issuance of common stock for cash (in shares)		28,000,000
Issuance of common stock for cash	268.2		268.2
Issuance of common stock for employee stock purchase plan, options and warrants (in shares)		700,000
Issuance of common stock for employee stock purchase plan, options and warrants	3.5		3.5
Restricted stock issued and related taxes (in shares)		700,000
Restricted stock issued and related taxes	(2.0)		(2.0)
Net income (loss)	(42.7)				(42.7)
Other comprehensive income (loss), net of tax	$ 0.3			0.3
Balance, end of period (in shares) at Dec. 31, 2017	103,297,525	103,300,000
Balance, end of period at Dec. 31, 2017	$ 511.5	$ 0.0	$ 1,233.7	$ (1.4)	$ (720.8)