Benefit Plans (Details Textual) (USD $)	12 Months Ended				12 Months Ended							12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2012 Employee stock ownership plan [Member]	Dec. 31, 2011 Employee stock ownership plan [Member]	Dec. 31, 2010 Employee stock ownership plan [Member]	Dec. 31, 2012 Minimum [Member]	Dec. 31, 2012 Stock Options [Member]	Dec. 31, 2011 Stock Options [Member]	Dec. 31, 2010 Stock Options [Member]	Dec. 31, 2012 Stock Options [Member] Minimum [Member]	Dec. 31, 2012 Stock Options [Member] Maximum [Member]	Dec. 31, 2012 Restricted Stock Units R S U [Member]	Dec. 31, 2011 Restricted Stock Units R S U [Member]	Dec. 31, 2012 Common Stock [Member]	Jun. 06, 2007 Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock remained available for grants of awards																	1,875,000
Minimum rate of exercise price granted																100.00%
Stock options granted									6,424,600
Stock options, Exercise prices lower									$ 11.74
Stock options, Exercise prices upper									$ 34.28
Purchase of shares									2,733,845
Stock option shares terminated									852,202
Stock option plans remain outstanding	2,838,553	3,086,019	3,344,450	3,504,319					2,838,553
Stock options vesting period									5 years
Stock options expiration after grant date												7 years	10 years
Options issued to non-employee advisors									0
Shares available for issuance of awards									1,561,002
Aggregate intrinsic value of options outstanding									$ 13,400,000	$ 16,900,000
Weighted average remaining contractual life									2 years 8 months 27 days	3 years 6 months 7 days
Intrinsic value for options exercisable									10,400,000	10,500,000
Weighted average remaining contractual life									2 years 4 months 10 days	3 years 2 months 19 days
Completion of the minimum of Period of employee stock ownership plan	12 months
Aggregate intrinsic value of options exercised and sold									3,700,000	3,700,000	3,600,000
Total unrecognized compensation expense net of forfeitures														6,100,000
Stock based compensation expense for restricted stock														1,800,000	2,600,000
Total unrecognized compensation cost									3,500,000
Expected recognition period of unrecognized compensation expense									1 year 7 months 6 days					3 years 3 months 18 days
Plan merged assets					16,400,000
Percentage of total common shares outstanding					2.00%
Dividends deducted					200,000	400,000	500,000
Tax benefit from dividends	100,000				100,000	200,000	200,000
Completion of the minimum of hours of employee stock ownership plan								1000 hours
Contribution to employee stock ownership plan					0	0	0
Shares outstanding, employee stock ownership plan					354,467
Benefit Plans (Textual) [Abstract]
Contribution to retirement plan	0	1,100,000	0
Enviroplex contribution to retirement plan	$ 0	$ 35,000	$ 0