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Long-Term Investments - Summary of Available-for-Sale Securities (Detail) - Failed Auction Security [Member] - USD ($)
Jun. 30, 2020
Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]    
Cost $ 3,000,000 $ 3,000,000
Gross Unrealized Losses 445,000 490,000
Estimated Fair Value $ 2,555,000 $ 2,510,000