Debt (Schedule Of Convertible Notes, Carrying Amount Details) (Detail) (Convertible Debt [Member], USD $)	Jun. 30, 2013		Dec. 31, 2012	Jun. 30, 2012
New 4.0% Notes [Member]
Debt Instrument [Line Items]
Principal amount	$ 105,322,000	[1]	$ 105,300,000	$ 105,322,000	[1]
Unamortized debt discount and financing costs	(3,000,000)		(4,400,000)
Net carrying amount of debt component	102,300,000		100,900,000
Carrying amount of equity component	8,900,000		8,900,000
New 4.25% Notes [Member]
Debt Instrument [Line Items]
Principal amount	97,000,000	[1]	97,000,000	97,000,000	[1]
Unamortized debt discount and financing costs	(3,700,000)		(4,900,000)
Net carrying amount of debt component	93,300,000		92,100,000
Carrying amount of equity component	$ 8,500,000		$ 8,500,000

[1] Dilutive shares associated with the New Convertible Notes are attributable to the weighted average premium value, in shares, of the conversion shares underlying the New Convertible Notes in excess of the respective principal amounts thereof.