Financial Instruments and Fair Value Disclosures - Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment of assets	$ 774,000	$ 774,028
Nonrecurring Fair Value Measurements [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment of assets		774,028
Investment in Foreign Bonds [Member] | Recurring Fair Value Measurements [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total investments		5,720
Money Market Funds | Recurring Fair Value Measurements [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total short-term investments			$ 135,300
Level 1 [Member] | Investment in Foreign Bonds [Member] | Recurring Fair Value Measurements [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total investments		$ 5,720
Level 1 [Member] | Money Market Funds | Recurring Fair Value Measurements [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total short-term investments			$ 135,300