Stockholders' Equity - Summary of Changes in Stockholders' Equity (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 28, 2014	Sep. 29, 2013	Sep. 28, 2014	Sep. 29, 2013
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders’ equity at beginning of period			$ 295.8	$ 324.1
Comprehensive loss:
Net loss	(10.9)	(9.9)	(75.8)	(29.8)
Foreign currency translation	(0.1)	(0.1)	(0.2)	0
Comprehensive loss	(11.0)	(10.0)	(76.0)	(29.8)
Exercise of stock options and warrants			(0.1)	0
Stock-based compensation			7.6	6.0
Employee stock purchase plan and restricted stock units settled in cash			3.9	1.6
Restricted stock units traded for taxes			(0.2)	(0.2)
Stockholders’ equity at end of period	$ 231.0	$ 301.7	$ 231.0	$ 301.7