Stockholders' Equity - Summary of Changes in Stockholders' Equity (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 28, 2015	Jun. 29, 2014	Jun. 28, 2015	Jun. 29, 2014
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders’ equity at beginning of period			$ 224.3	$ 295.8
Comprehensive loss:
Net loss	$ (15.0)	$ (49.9)	(31.3)	(64.9)
Change in cumulative translation adjustment	0.3	0.0	0.1	(0.1)
Comprehensive loss	(14.7)	(49.9)	(31.2)	(65.0)
Exercise of stock options and warrants			0.0	(0.1)
Stock-based compensation			4.0	4.7
Employee stock purchase plan and restricted stock units settled in cash			1.8	1.8
Restricted stock units traded for taxes			(0.2)	(0.1)
Stockholders’ equity at end of period	$ 198.7	$ 237.1	$ 198.7	$ 237.1