Stockholders' Equity - Summary of Changes in Stockholders' Equity (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 30, 2014	Mar. 31, 2013
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders’ equity at beginning of period	$ 295.8	$ 324.1
Comprehensive loss:
Net loss	(15.0)	(10.3)
Foreign currency translation	(0.1)	0.1
Comprehensive loss	(15.1)	(10.2)
Exercise of stock options and warrants	(0.1)	0
Stock-based compensation	1.8	1.9
Employee stock purchase plan and restricted stock units settled in cash	1.8	0
Restricted stock units traded for taxes	(0.1)	(0.2)
Stockholders’ equity at end of period	$ 284.1	$ 315.6