Benefit Plans (Details 1) (USD $)	12 Months Ended
	Dec. 31, 2012
Range One [Member]
Options outstanding and options exercisable by exercise price with the weighted average remaining contractual life for the options outstanding and the weighted average exercise price
Exercise price lower range limit	$ 10
Exercise price upper range limit	$ 15
Number Outstanding	20,000
Weighted Average Remaining Contractual Life (Years)	3 months
Weighted Average Exercise Price	$ 11.74
Number Exercisable	20,000
Weighted Average Exercise Price	$ 11.74
Range Two [Member]
Options outstanding and options exercisable by exercise price with the weighted average remaining contractual life for the options outstanding and the weighted average exercise price
Exercise price lower range limit	$ 15
Exercise price upper range limit	$ 20
Number Outstanding	420,608
Weighted Average Remaining Contractual Life (Years)	2 years 10 months 10 days
Weighted Average Exercise Price	$ 15.65
Number Exercisable	265,608
Weighted Average Exercise Price	$ 15.67
Range Three [Member]
Options outstanding and options exercisable by exercise price with the weighted average remaining contractual life for the options outstanding and the weighted average exercise price
Exercise price lower range limit	$ 20
Exercise price upper range limit	$ 25
Number Outstanding	1,161,150
Weighted Average Remaining Contractual Life (Years)	2 years 6 months 26 days
Weighted Average Exercise Price	$ 21.73
Number Exercisable	1,008,275
Weighted Average Exercise Price	$ 21.55
Range Four [Member]
Options outstanding and options exercisable by exercise price with the weighted average remaining contractual life for the options outstanding and the weighted average exercise price
Exercise price lower range limit	$ 25
Exercise price upper range limit	$ 30
Number Outstanding	688,295
Weighted Average Remaining Contractual Life (Years)	3 years 7 months 10 days
Weighted Average Exercise Price	$ 28.93
Number Exercisable	575,375
Weighted Average Exercise Price	$ 29.81
Range Five [Member]
Options outstanding and options exercisable by exercise price with the weighted average remaining contractual life for the options outstanding and the weighted average exercise price
Exercise price lower range limit	$ 30
Exercise price upper range limit	$ 35
Number Outstanding	548,500
Weighted Average Remaining Contractual Life (Years)	2 years 11 days
Weighted Average Exercise Price	$ 31.39
Number Exercisable	453,000
Weighted Average Exercise Price	$ 31.39
Range Six [Member]
Options outstanding and options exercisable by exercise price with the weighted average remaining contractual life for the options outstanding and the weighted average exercise price
Exercise price lower range limit	$ 10
Exercise price upper range limit	$ 35
Number Outstanding	2,838,553
Weighted Average Remaining Contractual Life (Years)	2 years 8 months 27 days
Weighted Average Exercise Price	$ 24.37
Number Exercisable	2,322,258
Weighted Average Exercise Price	$ 24.64