Fair Value Measurements - Fair Value Of Assets Measured On Recurring And Nonrecurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Secured Senior Notes	$ 933,871	$ 932,089
Recurring Items [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Cash and cash equivalents	102,713	94,410
Debt Security	70,722
Recurring Items [Member] | Convertible Senior Notes Due 2013 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Convertible Senior Notes	240,450	248,000
Recurring Items [Member] | Secured Senior Notes [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Secured Senior Notes	649,199	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	102,713	94,410
Debt Security	0
Quoted Prices in Activated Markets for Identical Assets (Level 1) [Member] | Recurring Items [Member] | Convertible Senior Notes Due 2013 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Convertible Senior Notes	240,450	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]
Secured Senior Notes	649,199	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
Debt Security	0
Significant Other Observable Inputs (Level 2) [Member] | Recurring Items [Member] | Convertible Senior Notes Due 2013 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Convertible 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]
Secured 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
Debt Security	70,722
Unobservable Inputs (Level 3) [Member] | Recurring Items [Member] | Convertible Senior Notes Due 2013 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Convertible 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]
Secured 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