Cash Equivalents and Investments (Footnote) (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Short-term Investments | Certificates of deposit and money market deposit accounts | Minimum
Cash and Cash Equivalents [Line Items]
Securities maturity period	1 month	1 month
Short-term Investments | Certificates of deposit and money market deposit accounts | Maximum
Cash and Cash Equivalents [Line Items]
Securities maturity period	12 months	12 months
Other assets | Certificates of deposit and money market deposit accounts | Minimum
Cash and Cash Equivalents [Line Items]
Securities maturity period	13 months	14 months
Other assets | Certificates of deposit and money market deposit accounts | Maximum
Cash and Cash Equivalents [Line Items]
Securities maturity period	18 months	36 months
Cash and cash equivalent | Open ended mutual funds | Maximum
Cash and Cash Equivalents [Line Items]
Securities maturity period	90 days