Earnings Per Share (Summary Of Earnings Per Share, Basic And Diluted) (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Earnings Per Share Basic And Diluted By Common Class [Line Items]
Net income	$ 59,648	$ 40,514	$ 156,128	$ 109,563
Weighted-average shares outstanding	83,229,000	79,790,000	82,435,000	79,093,000
Share-based payment awards classified as participating securities	773,000	1,029,000	825,000	1,212,000
Denominator for basic earnings per share	84,002,000	80,819,000	83,260,000	80,305,000
Dilutive securities	2,222,000	2,830,000	2,421,000	3,221,000
Denominator for diluted earnings per share	86,224,000	83,649,000	85,681,000	83,526,000
Basic earnings per share	$ 0.71	$ 0.50	$ 1.88	$ 1.36
Diluted earnings per share	$ 0.69	$ 0.48	$ 1.82	$ 1.31
Diluted earnings per share excludes antidilutive effect	200,000	400,000
Earnings Per Share, Basic [Member]
Earnings Per Share Basic And Diluted By Common Class [Line Items]
Net income	$ 59,648	$ 40,514		$ 109,563