Stockholders' Equity (Details Textual) (USD $)	1 Months Ended				12 Months Ended					12 Months Ended																					12 Months Ended				12 Months Ended
	Feb. 25, 2013	Apr. 30, 2012	Jul. 31, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011 Number_of_stock_repurchase	Dec. 31, 2010	Nov. 24, 2012	Dec. 27, 2010	Dec. 31, 2012 1999 plan [Member]	Dec. 31, 2012 2001 plan [Member]	Dec. 31, 2012 2004 plan [Member]	Dec. 31, 2012 2009 plan [Member]	Dec. 31, 2010 2009 plan [Member]	Dec. 31, 2012 2009 plan [Member] Maximum [Member]	Dec. 31, 2012 2009 plan [Member] Minimum [Member]	Dec. 31, 2012 Incentive Stock Options [Member]	Dec. 31, 2011 Incentive Stock Options [Member]	Dec. 31, 2010 Incentive Stock Options [Member]	Dec. 31, 2012 Performance Shares [Member]	Dec. 31, 2011 Performance Shares [Member]	Dec. 31, 2010 Performance Shares [Member]	Dec. 31, 2012 Non-vested options [Member]	Dec. 31, 2012 Non qualified stock options [Member]	Dec. 31, 2011 Non qualified stock options [Member]	Dec. 31, 2010 Non qualified stock options [Member]	Dec. 31, 2012 Restricted Stock [Member]	Dec. 31, 2011 Restricted Stock [Member]	Dec. 31, 2010 Restricted Stock [Member]	Dec. 31, 2009 Restricted Stock [Member]	Dec. 31, 2012 Stock Options [Member]	Dec. 31, 2011 Stock Options [Member]	Dec. 31, 2010 Stock Options [Member]	Dec. 31, 2009 Stock Options [Member]	Dec. 31, 2012 Performance Based Restricted Stock Unit [Member]
Stockholders Equity (Additional Textual) [Abstract]
Vesting period										3 years	3 years	3 years			4 years	3 years
Contractual maturity of plan										10 years	10 years	10 years	10 years
Shares registered										9,952,500	6,600,000	6,800,000	1,000,000
2004 Plan within fiscal 2005 vesting terms												1 year
Exercise of stock options, shares																				100,000											5,278,243	6,432,667	5,967,590
Unvested performance options																				500,000
Options expected to vest, end of year																				400,000											841,249
Fair value of performance-based stock options outstanding and expected to vest																				$ 1,100,000
New option granted					0									200,000							1,000,000											1,018,182	988,941
Exercise price of the new options														$ 4.84																		$ 4.65	$ 5.08
Options outstanding, weighted average exercise price																							$ 4.72								$ 6.05	$ 5.75	$ 5.71	$ 5.94
Weighted average fair value						$ 2.16	$ 2.59																$ 2.23
Tax benefit recorded																								4,700,000	9,800	0
Unrecognized stock-based compensation expense related to non-vested stock options																											2,000,000				1,000,000
Weighted average remaining contractual life																							7 years 2 months 12 days
Weighted average period																											25 months				14 months
Aggregate intrinsic value price per share					$ 8.94																						$ 8.94
Approximate units of performance restricted stock granted																											186,000
Performance criteria met for approximate units																											97,007								173,000
Approximate units outstanding																											582,212	1,096	50	50					181,000
Incremental stock option expense					3,421,506	3,038,300	3,682,675							10,000			500,000	1,300,000	1,900,000	100,000	300,000	100,000													700,000
Number of Options Outstanding																				600,000			1,000,000								6,321,076	7,576,493	7,507,236	8,780,017
Unvested share, expected to vest																				300,000
Aggregate intrinsic value, option outstanding					19,900,000
Weighted average fair value of options granted						$ 2.16	$ 2.59
Stockholders Equity (Textual) [Abstract]
Common stock, par value					$ 0.00001	$ 0.00001
Preferred stock, par value					$ 0.00001	$ 0.00001
Common stock, shares authorized					200,000,000	200,000,000
Preferred stock, shares authorized					25,000,000	25,000,000
Number of Repurchase Programs Authorized						2
Stock repurchase program authorized by BOD	25,000,000	20,000,000	20,000,000	12,500,000
Shares repurchased by company					3,800,000	7,464,583
Average cost of repurchase per share					$ 5.22	$ 4.35
Purchase of treasury stock					(19,995,950)	(32,498,856)
Option available for future grants					1,400,000
Nontransferable stock options to be received by officers, employees and director					24,352,500
Stock options eligible for exchange, exercise price									$ 8.00
Stock options eligible for exchange								900,000
Option tendered by employees								500,000
Option tendered by employees, percent								53.00%
Total fair value of option exercisable					18,300,000	13,900,000	18,700,000
Aggregate intrinsic value, option outstanding					19,900,000
Aggregate intrinsic value, options exercisable					15,500,000
Aggregate intrinsic value of unvested options					4,400,000
Total intrinsic value of options exercised					3,200,000	1,600,000	2,200,000
Share based compensation arrangement by share based payment award future tax benefit					$ 3,700,000	$ 2,800,000