Stockholders' Equity (Details 1) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Summary of stock options activity
Granted, Number of options	0
Stock Options [Member]
Summary of stock options activity
Options outstanding, beginning of year	7,576,493	7,507,236	8,780,017
Weighted average exercise price, Options outstanding, beginning of year	$ 5.75	$ 5.71	$ 5.94
Number of options, Granted under option exchange program			221,723
Weighted average exercise price, Granted under option exchange program			$ 4.84
Granted, Number of options		1,018,182	988,941
Weighted average exercise price, Granted		$ 4.65	$ 5.08
Number of options, Exercised	(784,383)	(539,923)	(502,205)
Weighted average exercise price, Exercised	$ 2.46	$ 2.64	$ 1.99
Number of options, Expired / terminated	(471,034)	(409,002)	(1,517,934)
Weighted average exercise price, Expired / terminated	$ 7.15	$ 6.38	$ 7.28
Number of options, Cancelled under option exchange program			(463,306)
Weighted average exercise price, Cancelled under option exchange program			$ 11.66
Options outstanding, end of year	6,321,076	7,576,493	7,507,236
Weighted average exercise price, Options outstanding, end of year	$ 6.05	$ 5.75	$ 5.71
Options exercisable, end of year	5,278,243	6,432,667	5,967,590
Weighted average exercise price, Options exercisable, end of year	$ 6.31	$ 6.02	$ 5.99
Options expected to vest, end of year	841,249
Weighted average exercise price, Options expected to vest, end of year	$ 4.62