Stock-based Compensation Expense (Details 2) (USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2012 Y
Range of Exercise Prices, $9.07-$20.00
Stock options outstanding and exercisable
Exercise price, low end of range (in dollars per share)	$ 9.07
Exercise price, high end of range (in dollars per share)	$ 20.00
Exercise price range, options outstanding (in shares)	1,273
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	3.27
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 15.57
Exercise price range, options exercisable (in shares)	1,273
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 15.57
Range of Exercise Prices, $20.01-$30.00
Stock options outstanding and exercisable
Exercise price, low end of range (in dollars per share)	$ 20.01
Exercise price, high end of range (in dollars per share)	$ 30.00
Exercise price range, options outstanding (in shares)	1,484
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	6.79
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 29.22
Exercise price range, options exercisable (in shares)	1,035
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 28.99
Range of Exercise Prices, $30.01-$40.00
Stock options outstanding and exercisable
Exercise price, low end of range (in dollars per share)	$ 30.01
Exercise price, high end of range (in dollars per share)	$ 40.00
Exercise price range, options outstanding (in shares)	13,413
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	7.42
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 36.11
Exercise price range, options exercisable (in shares)	6,815
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 35.09
Range of Exercise Prices, $40.01-$50.00
Stock options outstanding and exercisable
Exercise price, low end of range (in dollars per share)	$ 40.01
Exercise price, high end of range (in dollars per share)	$ 50.00
Exercise price range, options outstanding (in shares)	345
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	8.81
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 44.28
Exercise price range, options exercisable (in shares)	51
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 44.59
Range of Exercise Prices, $50.01-$60.00
Stock options outstanding and exercisable
Exercise price, low end of range (in dollars per share)	$ 50.01
Exercise price, high end of range (in dollars per share)	$ 60.00
Exercise price range, options outstanding (in shares)	2,191
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	9.11
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 53.14
Exercise price range, options exercisable (in shares)	591
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 54.73
Range of Exercise Prices, $60.01-$64.30
Stock options outstanding and exercisable
Exercise price, low end of range (in dollars per share)	$ 60.01
Exercise price, high end of range (in dollars per share)	$ 64.30
Exercise price range, options outstanding (in shares)	65
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	9.89
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 63.10