Stock-based Compensation Expense (Details 2) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 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)	2,352
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	2.98
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 15.52
Exercise price range, options exercisable (in shares)	2,352
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 15.52
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)	1,793
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	6.73
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 29.05
Exercise price range, options exercisable (in shares)	1,304
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 28.80
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)	16,299
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	7.53
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 36.10
Exercise price range, options exercisable (in shares)	8,660
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 35.23
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)	403
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	8.75
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 44.42
Exercise price range, options exercisable (in shares)	92
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 44.53
Range of Exercise Prices, $50.01-$57.27
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)	$ 57.27
Exercise price range, options outstanding (in shares)	2,026
Exercise price range, options outstanding, weighted-average remaining contractual life (in years)	9.20
Exercise price range, options outstanding, weighted-average exercise price (in dollars per share)	$ 52.18
Exercise price range, options exercisable (in shares)	413
Exercise price range, options exercisable, weighted-average exercise price (in dollars per share)	$ 52.82