Earnings Per Share (Computation Of Net Income Per Share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Basic earnings per share:
Net income	$ 29,471	$ 6,164	$ 32,160	$ 1,580
Weighted-average common shares outstanding - Basic	58,192	55,526	57,089	55,491
Basic earnings per share (in dollars per share)	$ 0.51	$ 0.11	$ 0.56	$ 0.03
Diluted earnings per share:
Net income	29,471	6,164	32,160	1,580
Senior Convertible Notes interest expense, net of tax	0	48	49	98
Numerator for diluted earnings per share	$ 29,471	$ 6,212	$ 32,209	$ 1,678
Shares used in computation:
Weighted-average common shares outstanding - Basic	58,192	55,526	57,089	55,491
Senior Convertible Notes shares	564	2,331	1,442	2,331
Employee stock options	1,834	952	1,838	1,056
Weighted-average number of shares - Diluted	60,590	58,809	60,369	58,878
Diluted earnings per share (in dollars per share)	$ 0.49	$ 0.11	$ 0.53	$ 0.03