Fair Value Measurements - Schedule of Fair Value of Borrowings (Detail) - 5.0% Exchangeable Senior Notes due March 2021 [Member] - Exchangeable Senior Notes [Member] - Significant Other Observable Inputs (Level 2) [Member] $ in Thousands	Dec. 31, 2020 USD ($)
Borrowings:
Carrying amount of senior notes	$ 83,479
Estimated fair value of senior notes	$ 145,466