Equity Incentive Plans and Stock-Based Compensation (Details 5) (USD $)	1 Months Ended	3 Months Ended			12 Months Ended			0 Months Ended	1 Months Ended	12 Months Ended				12 Months Ended
	Apr. 30, 2009	Jun. 30, 2012	Dec. 31, 2013	Mar. 31, 2006	Dec. 31, 2013 Stock Compensation Plan	Dec. 31, 2012 Stock Compensation Plan	Dec. 31, 2011 Stock Compensation Plan	Sep. 27, 2013 Employee Stock Purchase Plans	Apr. 30, 2012 Employee Stock Purchase Plans	Dec. 31, 2013 Employee Stock Purchase Plans plan	Dec. 31, 2012 Employee Stock Purchase Plans plan	Dec. 31, 2011 Employee Stock Purchase Plans plan	Mar. 31, 2006 Employee Stock Purchase Plans	Dec. 31, 2013 Stock Option Plans	Dec. 31, 2012 Stock Option Plans	Dec. 31, 2011 Stock Option Plans	Dec. 31, 2013 Shares including nonvested equity stock and stock units	Dec. 31, 2012 Shares including nonvested equity stock and stock units	Dec. 31, 2011 Shares including nonvested equity stock and stock units	Dec. 31, 2013 Minimum Stock Option Plans	Dec. 31, 2012 Minimum Stock Option Plans	Dec. 31, 2011 Minimum Stock Option Plans	Dec. 31, 2013 Maximum Stock Option Plans	Dec. 31, 2012 Maximum Stock Option Plans	Dec. 31, 2011 Maximum Stock Option Plans	Dec. 31, 2013 Option One	Dec. 31, 2013 Option Two
Stock-Based Compensation
Required service period																										60 months	48 months
Number of employee stock purchase plans										1	1	1
Minimum number of hours of weekly employment in order to qualify for eligibility in the plan										20 hours	20 hours	20 hours
Number of shares reserved under the 2006 Purchase Plan			21,400,000	8,400,000									1,600,000
Increase in shares approved for issuance	6,500,000	6,500,000							1,500,000
Employee Stock Purchase Plan, Number Of Additional SharesToBe Authorized								1,500,000
Minimum number of months of employment in a fiscal year in order to qualify for eligibility in the plan										5 months	5 months	5 months
Offering period (in months)										6 months	6 months	6 months
Percentage of the price at the beginning of the offering period or price at the end of each offering period to derive purchase price										85.00%	85.00%	85.00%
Maximum share value per employee in any calendar year										$ 25,000	$ 25,000	$ 25,000
Shares issued under employee stock purchase plans										1,063,283	731,449	271,804
Weighted average price per share of shares issued (in dollars per share)										$ 4.87	$ 4.21	$ 15.62
Shares available for issuance					2,527,428.000					19,232
Options granted (in shares)														2,084,276	7,789,220	2,357,001
Estimated total grant date fair value														5,400,000	32,700,000	24,200,000
Stock-based compensation										1,500,000	2,200,000	1,700,000		10,400,000	15,000,000	19,600,000	3,100,000	5,300,000	6,700,000
Unrecognized compensation cost net of expected forfeitures														16,900,000			3,700,000
Expected weighted-average period for recognition of compensation cost (in years)										4 months				2 years 3 months 1 day			2 years 3 months 18 days
Total fair value of options vested														64,300,000	80,000,000	144,800,000
Total intrinsic value of options exercised														1,300,000	200,000	6,200,000
Total proceeds received and receivable from employee stock option exercises														3,300,000	1,000,000	7,400,000
Total fair value of nonvested equity stock units at grant date																	$ 3,300,000	$ 4,800,000	$ 6,700,000
Valuation assumptions
Dividend yield (as a percent)					0.00%	0.00%	0.00%
Expected stock price volatility rate minimum (as a percent)										44.00%	56.00%	56.00%		45.00%	57.00%	50.00%
Expected stock price volatility rate maximum (as a percent)										48.00%	63.00%	78.00%		47.00%	68.00%	75.00%
Risk free interest rate (as a percent)										0.10%	0.20%	0.10%
Risk free interest rate minimum (as a percent)														0.80%	0.60%	1.40%
Risk free interest rate maximum (as a percent)														1.50%	0.90%	2.80%
Expected term (in years)										0 years 6 months	0 years 6 months	0 years 6 months								5 years 4 months 25 days	5 years 6 months	6 years	5 years 6 months	5 years 8 months 12 days	6 years 1 month 6 days
Weighted average grant date fair value (in dollars per share)														$ 2.60	$ 3.57	$ 10.27
Weighted-average fair value of purchase rights granted under the purchase plan (in dollars per share)										$ 1.96	$ 1.58	$ 6.16					$ 6.92	$ 6.43	$ 17.86
Nonvested equity stock and stock units
Nonvested at the beginning of the period (in shares)																	922,491	763,510	718,007
Granted (in shares)																	473,074	742,009	374,838
Vested (in shares)																	(478,214)	(393,383)	(314,401)
Forfeited (in shares)																	(287,702)	(189,645)	(14,934)
Nonvested at the end of the period (in shares)																	629,649	922,491	763,510
Weighted-Average Grant-Date Fair Value
Nonvested at the beginning of the period (in dollars per share)																	$ 10.24	$ 18.02	$ 18.23
Granted (in dollars per share)										$ 1.96	$ 1.58	$ 6.16					$ 6.92	$ 6.43	$ 17.86
Vested (in dollars per share)																	$ 9.81	$ 17.38	$ 18.15
Forfeited (in dollars per share)																	$ 9.18	$ 11.77	$ 21.76
Nonvested at the end of the period (in dollars per share)																	$ 8.56	$ 10.24	$ 18.02