Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 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	$ 75,500,000	$ 49,000,000
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	$ 26,500,000
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	$ 157,000,000		$ 98,000,000
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	$ 59,000,000