Net Income (Loss) Per Share - Numerators and Denominators of Basic and Diluted Net Income (Loss) Per Share Computations (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 28, 2012	Jun. 29, 2012	Mar. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Earnings Per Share [Line Items]
Net income (loss) (numerator)	$ 4,804	$ (8,230)	$ 17	$ (7,528)	$ 4,327	$ 3,546	$ 390	$ 516	$ (10,937)	$ 8,779	$ (4,335)
Shares calculation (denominator):
Weighted average shares outstanding - basic									116,457	115,175	101,487
Effect of Dilutive Securities:
Potential common stock relating to stock options, restricted stock units and ESPP										1,252
Weighted averages shares outstanding - diluted									116,457	116,427	101,487
Net income (loss) per share - basic	$ 0.04	$ (0.07)	$ 0.00	$ (0.06)	$ 0.04	$ 0.03	$ 0.00	$ 0.00	$ (0.09)	$ 0.08	$ (0.04)
Net income (loss) per share - diluted	$ 0.04	$ (0.07)	$ 0.00	$ (0.06)	$ 0.04	$ 0.03	$ 0.00	$ 0.00	$ (0.09)	$ 0.08	$ (0.04)