Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Jan. 02, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value assets liabilities transfers between valuation levels		$ 0	$ 0
Gram Games [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration payable, total years		3 years
Contingent consideration obligation	$ 72,800,000	$ 72,800,000	$ 49,000,000.0
Gram Games [Member] | Research and Development Expense [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration obligation, expense recognized	(2,700,000)	$ 23,800,000
Small Giant [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration payable, total years		3 years
Contingent consideration obligation	183,600,000	$ 183,600,000		$ 98,000,000.0
Small Giant [Member] | Research and Development Expense [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration obligation, expense recognized	$ 26,600,000	$ 85,600,000