Common Stock (Schedule Of Information Related To Stock Repurchase Programs) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009		Dec. 31, 2008
Class of Stock [Line Items]
Additional Shares Authorized For Repurchase
Total number of shares purchased	4,478,428	[1]
Average price paid per share for forfeited restricted shares	$ 0.01
Total number of shares purchased as part of publicly announced programs	4,457,428
Average price paid per share for shares purchased as part of publicly announced program	$ 30.35
Aggregate purchase price paid	$ 135,298
Maximum number of shares that may yet be purchased under the program							4,713,548
Restricted shares forfeited under stock purchase plan			8,000		13,000
Stock Repurchase Programs 2009 [Member]
Class of Stock [Line Items]
Additional Shares Authorized For Repurchase
Total number of shares purchased					2,574,209	[1]
Average price paid per share for forfeited restricted shares					0.01
Total number of shares purchased as part of publicly announced programs					2,561,209
Average price paid per share for shares purchased as part of publicly announced program					24.71
Aggregate purchase price paid					63,288
Maximum number of shares that may yet be purchased under the program					2,152,339
Stock Repurchase Programs 2010 [Member]
Class of Stock [Line Items]
Additional Shares Authorized For Repurchase
Total number of shares purchased			301,933	[1]
Average price paid per share for forfeited restricted shares			0.01
Total number of shares purchased as part of publicly announced programs			293,933
Average price paid per share for shares purchased as part of publicly announced program			39.22
Aggregate purchase price paid			11,528
Maximum number of shares that may yet be purchased under the program			1,858,406
Stock Repurchase Programs 2011 [Member]
Class of Stock [Line Items]
Additional Shares Authorized For Repurchase
Total number of shares purchased	1,602,286	[1]
Average price paid per share for forfeited restricted shares	$ 0.01
Total number of shares purchased as part of publicly announced programs	1,602,286
Average price paid per share for shares purchased as part of publicly announced program	$ 37.75
Aggregate purchase price paid	$ 60,482
Maximum number of shares that may yet be purchased under the program	256,120

[1] During 2010 and 2009, there were 8,000 and 13,000, respectively, of restricted shares that were forfeited by former employees pursuant to the terms of our restricted stock purchase plan which are included in the total number of shares purchased. No such forfeitures occurred during 2011.