Stock Option and Purchase Plans (Details) (USD $)	0 Months Ended	1 Months Ended	12 Months Ended						12 Months Ended
	Apr. 30, 2010 Stand-Alone Stock Option Agreement	Jan. 31, 2014 Stock options	Dec. 31, 2013 Stock options	Dec. 31, 2012 Stock options	Dec. 31, 2011 Stock options	Dec. 31, 2013 Restricted stock units	Dec. 31, 2012 Restricted stock units	Mar. 29, 2010 2001 Stock Option Plan	Dec. 31, 2013 2010 Equity Incentive Plan	Jun. 25, 2010 2010 Equity Incentive Plan
Stock Option and Purchase Plans
Shares reserved and unissued			1,976,823					32,000
Expiration period of awards granted			10 years
Vesting period									4 years
Number of shares authorized										8,400,000
Number of shares reserved but not issued pursuant to awards under 2001 Stock Option Plan										99,975
Number of shares reserved but not issued pursuant to options outstanding under 2001 Stock Option Plan										8,111,273
Number of Restricted Stock Units
Restricted stock units outstanding at the beginning of the period (in shares)						35,000
Granted (in shares)						144,500	35,000
Vested (in shares)						(33,296)
Forfeited (in shares)						(146,204)
Restricted stock units outstanding at the end of the period (in shares)							35,000
Weighted Average Grant Date Fair Value
Restricted stock units outstanding at the beginning of the period (in dollars per shares)						$ 24.88
Granted (in dollars per share)						$ 12.63	$ 24.88
Vested (in dollars per share)						$ (14.15)
Forfeited (in dollars per share)						$ (13.83)
Restricted stock units outstanding at the end of the period (in dollars per shares)							$ 24.88
Number of Shares
Balance at beginning of year (in shares)		8,906,451	8,510,917	8,575,434	7,919,013
Granted (in shares)	400,000	1,128,100	4,166,292	2,850,118	1,289,790
Exercised (in shares)			(2,375,688)	(2,648,882)	(482,172)
Cancelled (in shares)			(1,395,070)	(265,753)	(151,197)
Balance at end of year (in shares)			8,906,451	8,510,917	8,575,434
Exercisable at end of year (in shares)			6,616,555	4,781,301	6,120,210
Weighted-Average Exercise Price
Balance at beginning of year (in dollars per share)		$ 12.06	$ 10.33	$ 6.17	$ 5.71
Granted (in dollars per share)			$ 12.86	$ 17.80	$ 8.72
Exercised (in dollars per share)			$ 5.79	$ 5.00	$ 4.88
Cancelled (in dollars per share)			$ 14.54	$ 9.28	$ 8.32
Balance at end of year (in dollars per share)			$ 12.06	$ 10.33	$ 6.17
Exercisable at end of year (in dollars per share)			$ 11.00	$ 6.32	$ 5.38
Weighted average grant-date fair value of options granted during the year (in dollars per share)			$ 8.32	$ 11.91	$ 5.91