Earnings Per Share (Schedule Of Convertible Note Premium Share Information) (Details) (Convertible Debt [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
2011 4.25% Notes [Member]
Earnings Per Share [Line Items]
Number of conversion shares, principal amount	6,268	6,268	6,268	6,268
Weighted average premium value	$ 139,170	$ 91,837	$ 140,047	$ 87,433
Weighted average equivalent premium shares	3,693	3,048	3,703	2,971
2011 4.25% Notes [Member] | Weighted Average [Member]
Earnings Per Share [Line Items]
Weighted average actual per share price	$ 37.68	$ 30.13	$ 37.82	$ 29.43
2011 4.0% Notes [Member]
Earnings Per Share [Line Items]
Number of conversion shares, principal amount		6,683		6,683
Weighted average premium value		$ 96,021		$ 91,325
Weighted average equivalent premium shares	3,300	3,187	3,600	3,104
2011 4.0% Notes [Member] | Weighted Average [Member]
Earnings Per Share [Line Items]
Weighted average actual per share price		$ 30.13		$ 29.43