Investments - Summary of Equity Investments (Detail) - USD ($) $ in Thousands |
Dec. 31, 2018 |
Dec. 31, 2017 |
---|---|---|
Schedule Of Available For Sale Securities [Line Items] | ||
Investment in equities | $ 16,911 | $ 0 |
Cost Method of Accounting [Member] | ||
Schedule Of Available For Sale Securities [Line Items] | ||
Investment in equities | 15,066 | |
Available for sale method [Member] | ||
Schedule Of Available For Sale Securities [Line Items] | ||
Investment in equities | $ 1,845 |