Changes In Stockholders' Equity (Schedule Of Changes In Common Stock, Additional Paid-In Capital And Accumulated Other Comprehensive Income/(Loss) Accounts) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Stockholders' Equity [Line Items]
Balance, December 31, 2011	$ 609,581
Balance, shares, December 31, 2011	39,677,291
Unrealized income on available for sale securities, net of tax	35		(54)
Exercise of stock options, shares	181,000
Cash settlement of share-based compensation			(4,133)
Balance, March 31, 2012	587,763
Balance, shares, March 31, 2012	39,919,972
Common Stock [Member]
Stockholders' Equity [Line Items]
Balance, December 31, 2011	397
Balance, shares, December 31, 2011	39,678,000
Exercise of stock options	1
Exercise of stock options, shares	149,000
Forfeitures of restricted stock, shares	(5,000)
Issuances of restricted stock	1
Issuances of restricted stock, shares	98,000
Balance, March 31, 2012	399
Balance, shares, March 31, 2012	39,920,000
Additional Paid-In Capital [Member]
Stockholders' Equity [Line Items]
Balance, December 31, 2011	389,166
Exercise of stock options	3,643
Net excess tax benefit from share-based compensation	2,759
Issuance of common stock under the Employee Stock Purchase Program	76
Issuances of restricted stock	(1)
Compensatory arrangements	2,442	[1]
Balance, March 31, 2012	398,085
Accumulated Other Comprehensive Income [Member]
Stockholders' Equity [Line Items]
Balance, December 31, 2011	13
Unrealized income on available for sale securities, net of tax	35
Balance, March 31, 2012	$ 48

[1] Share-based compensation expense includes equity-settled awards only.