Earnings Per Share (Schedule Of Convertible Note Premium Share Information) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 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
Premium value	$ 89,341	$ 108,864	$ 122,748	$ 94,728
2011 4.25% Notes [Member] | Convertible Debt [Member]
Earnings Per Share [Line Items]
Per share price, actual average	$ 29.73	$ 32.84	$ 35.06	$ 30.59
Premium shares	3,005	3,314	3,501	3,097
2011 4.0% Notes [Member]
Earnings Per Share [Line Items]
Number of conversion shares, principal amount		6,683		6,683
Premium value		$ 114,176		$ 99,104
2011 4.0% Notes [Member] | Convertible Debt [Member]
Earnings Per Share [Line Items]
Per share price, actual average		$ 32.84		$ 30.59
Premium shares		3,476	2,400	3,240