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		6 Months Ended		3 Months Ended		3 Months Ended			3 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Common Stock [Member]	Dec. 31, 2011 Common Stock [Member]	Jun. 30, 2012 Additional Paid-In Capital [Member]		Dec. 31, 2011 Additional Paid-In Capital [Member]	Jun. 30, 2012 Accumulated Other Comprehensive Income [Member]	Dec. 31, 2011 Accumulated Other Comprehensive Income [Member]
Stockholders' Equity [Line Items]
Balance, December 31, 2011			$ 609,581			$ 397			$ 389,166		$ 13
Balance, shares, December 31, 2011			39,677,291			39,678,000
Unrealized income on available for sale securities, net of tax	24	(15)	59	(69)						24
Exercise of stock options					2		5,434
Exercise of stock options, shares	224,000				224,000
Net excess tax benefit from share-based compensation							4,403
Issuance of common stock under the Employee Stock Purchase Program							172
Forfeitures of restricted stock, shares					(10,000)
Issuances of restricted stock					1		(1)
Issuances of restricted stock, shares					98,000
Compensatory arrangements							4,709	[1]
Balance, June 30, 2012	$ 644,776		$ 644,776		$ 400	$ 397	$ 403,883		$ 389,166	$ 37	$ 13
Balance, shares, June 30, 2012	39,989,734		39,989,734		39,990,000	39,678,000

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