Shareholders' Equity (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs included in consolidated net loss (in dollars)	$ 11,746,000	$ 7,551,000	$ 4,911,000
Weighted Average Grant Date Fair Value
Common stock reserved for share-based awards outstanding and available future grants	16,305,984
Continuing operations
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs included in consolidated net loss (in dollars)	11,746,000	7,282,000	4,540,000
Discontinued operations
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs included in consolidated net loss (in dollars)	0	269,000	371,000
Non-employee directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs included in consolidated net loss (in dollars)	558,000	517,000	349,000
RSUs
Number of RSUs
Nonvested shares outstanding at the beginning of the period (in shares)	1,685,000
Granted (in shares)	3,244,000
Vested (in shares)	(1,770,000)
Forfeited (in shares)	(410,000)
Nonvested shares outstanding at the end of the period (in shares)	2,749,000	1,685,000
Weighted Average Grant Date Fair Value
Nonvested shares outstanding at the beginning of the period (in dollars per share)	$ 4.43
Granted (in dollars per share)	$ 4.12
Vested (in dollars per share)	$ 4.29
Forfeited (in dollars per share)	$ 4.06
Nonvested shares outstanding at the end of the period (in dollars per share)	$ 4.09	$ 4.43
Total fair value (in dollars)	6,800,000	2,900,000	2,800,000
Total unrecognized compensation cost (in dollars)	9,300,000
Weighted average period for recognition of unrecognized stock-based compensation expense	2 years 0 months 4 days
RSUs | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year
RSUs | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
RSUs | Non-employee directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of common stock granted initial grant	100,000
Value of common stock granted annual grant	100,000
RSUs | Non-employee directors | Initial grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
RSUs | Non-employee directors | Annual grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year
Stock option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual terms	10 years
Weighted average assumptions used to value options granted and the grant date fair value
Expected life (in years)		4 years 4 months 24 days	4 years 2 months 12 days
Risk-free interest rate		0.63%	1.34%
Expected volatility		70.00%	67.00%
Dividend yield		0.00%	0.00%
Fair value		$ 2.13	$ 2.55
Number of Options
Outstanding at the beginning of the period (in shares)	8,115,000
Granted (in shares)	0
Exercised (in shares)	(635,000)
Expired or cancelled (in shares)	(1,801,000)
Forfeited (in shares)	(302,000)
Outstanding at the end of the period (in shares)	5,377,000	8,115,000
Vested and expected to vest at the end of the period (in shares)	5,336,000
Exercisable at the end of the period (in shares)	4,375,000
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 4.58
Granted (in dollars per share)	$ 0.00
Exercised (in dollars per share)	$ 3.43
Expired or canceled (in dollars per share)	$ 6.00
Forfeited (in dollars per share)	$ 4.42
Outstanding at the end of the period (in dollars per share)	$ 4.33	$ 4.58
Vested and expected to vest at the end of the period (in dollars per share)	$ 4.34
Exercisable at the end of the period (in dollars per share)	$ 4.55
Weighted Average Remaining Contractual Term
Outstanding at the end of the period	3 years 2 months 19 days
Vested and expected to vest at the end of the period	3 years 2 months 9 days
Exercisable at the end of the period	2 years 10 months 10 days
Aggregate Intrinsic Value
Outstanding at the end of the period	3,500,000
Vested and expected to vest at the end of period	3,469,000
Exercisable at the end of the period	2,682,000
Total intrinsic value of options exercised	500,000	300,000	2,100,000
Stock option | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual terms	10 years
2004 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock authorized for issuance	20,350,000
Number of share available for future grants	8,180,639
2004 Plan | Stock option | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual terms	4 years
Contractual terms for awards granted during last three fiscal years	5 years
2004 Plan | Stock option | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual terms	10 years
Expiration term	10 years
Contractual terms for awards granted during last three fiscal years	7 years
ESPP
Weighted Average Grant Date Fair Value
Contribution of compensation by the employees per calendar year, percentage	10.00%
Contribution of compensation by the employees per calendar year	$ 10,000
Percentage of the discount fair market value of common stock	95.00%
Offering period	3 months
Number of shares issued	206,000	281,000	442,000