Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (Fair Value, Measurements, Recurring, USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments, current	$ 7,250
Restricted investments, noncurrent	647
Total assets	7,897
Warrants	9,006	65,193
Total liabilities	9,006	65,193
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments, current	7,250
Restricted investments, noncurrent	647
Total assets	7,897
Warrants
Total liabilities
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments, current
Restricted investments, noncurrent
Total assets
Warrants
Total liabilities
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted investments, current
Restricted investments, noncurrent
Total assets
Warrants	9,006	65,193
Total liabilities	$ 9,006	$ 65,193