Debt (Schedule Of Convertible Notes, Carrying Amount Details) (Detail) (Convertible Debt [Member], USD $)	Sep. 30, 2012		Dec. 31, 2011	Sep. 30, 2011
New 4.0% Notes [Member]
Debt Instrument [Line Items]
Principal amount	$ 105,322,000	[1]		$ 105,300,000	[1]
Unamortized debt discount and financing costs	(5,100,000)
Net carrying amount of debt component	100,200,000		98,200,000
Carrying amount of equity component	8,900,000
New 4.25% Notes [Member]
Debt Instrument [Line Items]
Principal amount	97,000,000	[1]		97,000,000	[1]
Unamortized debt discount and financing costs	(5,400,000)
Net carrying amount of debt component	91,600,000		89,900,000
Carrying amount of equity component	$ 8,500,000

[1] Dilutive shares associated with the New Notes are attributable to the premium over the respective conversion prices.