Changes In Stockholders' Equity (Schedule Of Changes In Common Stock, Additional Paid-In Capital And Accumulated Other Comprehensive Gain (Loss) Accounts) (Details) (USD $) In Thousands, except Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011		Jun. 30, 2010
Balance, December 31, 2010			$ 628,444
Balance shares, December 31, 2010			38,872,663
Unrealized loss on available for sale securities, net of tax	(15)	(152)	(69)		(238)
Exercise of stock options, shares			644,000
Balance, June 30, 2011	539,303		539,303
Balance shares, June 30, 2011	39,655,227		39,655,227
Common Stock [Member]
Balance, December 31, 2010			389
Balance shares, December 31, 2010			38,873,000
Exercise of stock options			6
Exercise of stock options, shares			644,000
Forfeitures of restricted stock			1
Forfeitures of restricted stock, shares			(31,000)
Issuances of restricted stock			(2)
Issuances of restricted stock, shares			169,000
Balance, June 30, 2011	394		394
Balance shares, June 30, 2011	39,655,000		39,655,000
Additional Paid-In Capital [Member]
Balance, December 31, 2010			373,764
Exercise of stock options			9,804
Net excess tax benefit from share-based compensation			6,477
Issuance of common stock under the Employee Stock Purchase Program			170
Forfeitures of restricted stock			(1)
Issuances of restricted stock			1
Cash settlement of share-based compensation			(4,133)
Compensatory arrangements			5,582	[1]
Balance, June 30, 2011	391,664		391,664
Accumulated Other Comprehensive Gain/(Loss) [Member]
Balance, December 31, 2010			137
Unrealized loss on available for sale securities, net of tax			(69)
Balance, June 30, 2011	$ 68		$ 68

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