Net Income Per Share (Computation Of Net Income Per Share) (Details) (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Net Income Per Share [Abstract]
Net income	$ 62,460	$ 37,967	$ 190,907	$ 113,758
Weighted-average common shares outstanding	52,569	52,142	52,599	52,510
Basic earnings per share	$ 1.19	$ 0.73	$ 3.63	$ 2.17
Employee stock options and employee stock purchase plan shares	1,301	1,789	1,409	1,831
Weighted-average number of shares	53,870	53,931	54,008	54,341
Diluted earnings per share	$ 1.16	$ 0.70	$ 3.53	$ 2.09