Net Income (Loss) Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		12 Months Ended		3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2014 Common stock options	Mar. 31, 2013 Common stock options	Mar. 31, 2014 Restricted Stock [Member]	Mar. 31, 2013 Restricted Stock [Member]	Mar. 31, 2014 Restricted stock units	Mar. 31, 2013 Restricted stock units	Dec. 31, 2013 Convertible Debt [Member]	Dec. 10, 2013 Convertible Debt [Member]
Earnings Per Share, Basic and Diluted [Abstract]
Net Income (Loss) Attributable to Parent	$ 5,295	$ (9,334)
Shares used in computing basic net income (loss) per share	63,405	62,189
Shares used in computing diluted net income (loss) per share	66,017	62,189
Basic net income (loss) per share (usd per share)	$ 0.08	$ (0.15)
Diluted net income (loss) per share (usd per share)	$ 0.08	$ (0.15)
Weighted Average Number Diluted Shares Outstanding Adjustment [Abstract]
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements, Employee Stock Options	2,027	0
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements, Restricted Stock	152	0
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements, Restricted Stock Units (RSUs)	433	0
Incremental Common Shares Attributable to Share-based Payment Arrangements	2,612	0
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,153	3,717			1,153	2,768	0	492	0	457
Convertible notes	$ 67,901		$ 67,101									$ 86,300
Stated interest rate											2.25%
Potential Dilutive Effect of Securities [Abstract]
Conversion of the Notes			3,588	0