Fair Value Measurements (Fair Value Of Assets Measured On A Recurring And Nonrecurring Basis) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Recurring Items [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Cash and cash equivalents	$ 107,798	$ 94,410
Recurring Items [Member] | Convertible Senior Notes [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Senior Notes	272,800	248,000
Recurring Items [Member] | Secured Senior Notes [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Senior Notes	731,350	702,700
Nonrecurring Items [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets held for sale	675	675
Quoted Prices In Activated Markets For Identical Assets (Level 1) [Member] | Recurring Items [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Cash and cash equivalents	107,798	94,410
Quoted Prices In Activated Markets For Identical Assets (Level 1) [Member] | Recurring Items [Member] | Convertible Senior Notes [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Senior Notes	272,800	248,000
Quoted Prices In Activated Markets For Identical Assets (Level 1) [Member] | Recurring Items [Member] | Secured Senior Notes [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Senior Notes	731,350	702,700
Quoted Prices In Activated Markets For Identical Assets (Level 1) [Member] | Nonrecurring Items [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets held for sale	0	0
Significant Other Observable Inputs (Level 2) [Member] | Recurring Items [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Cash and cash equivalents	0	0
Significant Other Observable Inputs (Level 2) [Member] | Recurring Items [Member] | Convertible Senior Notes [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Senior Notes	0	0
Significant Other Observable Inputs (Level 2) [Member] | Recurring Items [Member] | Secured Senior Notes [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Senior Notes	0	0
Significant Other Observable Inputs (Level 2) [Member] | Nonrecurring Items [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets held for sale	0	0
Unobservable Inputs (Level 3) [Member] | Recurring Items [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Cash and cash equivalents	0	0
Unobservable Inputs (Level 3) [Member] | Recurring Items [Member] | Convertible Senior Notes [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Senior Notes	0	0
Unobservable Inputs (Level 3) [Member] | Recurring Items [Member] | Secured Senior Notes [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Senior Notes	0	0
Unobservable Inputs (Level 3) [Member] | Nonrecurring Items [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets held for sale	$ 675	$ 675