Long-Term Investments - Amortized Cost and Estimated Fair Value of Available-for-Sale Securities by Contractual Maturities (Detail) $ in Thousands	Dec. 31, 2019 USD ($)
Available-for-sale Securities, Debt Maturities [Abstract]
Due in twenty to forty years, Cost	$ 3,000
Due in twenty to forty years, Estimated Fair Value	$ 2,510