Stock-Based Compensation (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2014
Outstanding options
Number outstanding (in shares)	6,633,622
Weighted-average remaining contractual life	3 years 22 days
Weighted-average exercise price (in dollars per share)	$ 8.12
Exercisable options
Number outstanding (in shares)	4,875,757
Weighted-average exercise price (in dollars per share)	$ 7.37
$4.39 to $6.59
Information about stock options outstanding
Low end of exercise price range (in dollars per share)	$ 4.39
Outstanding options
Number outstanding (in shares)	1,580,299
Weighted-average remaining contractual life	1 year 6 months 29 days
Weighted-average exercise price (in dollars per share)	$ 5.76
Exercisable options
Number outstanding (in shares)	1,580,299
Weighted-average exercise price (in dollars per share)	$ 5.76
$6.64 to $10.05
Outstanding options
Number outstanding (in shares)	4,082,301
Weighted-average remaining contractual life	2 years 11 months 5 days
Weighted-average exercise price (in dollars per share)	$ 8.20
Exercisable options
Number outstanding (in shares)	3,248,458
Weighted-average exercise price (in dollars per share)	$ 8.08
$10.08 to $14.41
Outstanding options
Number outstanding (in shares)	971,022
Weighted-average remaining contractual life	5 years 11 months 19 days
Weighted-average exercise price (in dollars per share)	$ 11.63
Exercisable options
Number outstanding (in shares)	47,000
Weighted-average exercise price (in dollars per share)	$ 12.17