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
	Mar. 31, 2014	Mar. 31, 2013
2011 4.0% Notes [Member]
Earnings Per Share [Line Items]
Number of conversion shares, principal amount	6,683	6,683
Weighted average premium value	$ 148,360	$ 86,316
Weighted average equivalent premium shares	3,909	3,010
2011 4.0% Notes [Member] | Weighted Average [Member]
Earnings Per Share [Line Items]
Weighted average actual per share price	$ 37.96	$ 28.68
2011 4.25% Notes [Member]
Earnings Per Share [Line Items]
Number of conversion shares, principal amount	6,268	6,268
Weighted average premium value	$ 140,925	$ 82,735
Weighted average equivalent premium shares	3,712	2,885
2011 4.25% Notes [Member] | Weighted Average [Member]
Earnings Per Share [Line Items]
Weighted average actual per share price	$ 37.96	$ 28.68