Fair Value Measurements - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liquid investments, original maturities	90 days
Perpetual growth rate for deferred consideration	1.50%	1.50%
Discount rate for deferred consideration	10.00%	10.00%
Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gold forward-looking price range	$ 1,535	$ 1,294
Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gold forward-looking price range	$ 2,328	$ 2,621