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Financial Instruments - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financial Instruments and Fair Value [Line Items]
Available-for-sale securities, realized gain	$ 4,000,000	$ 1,100,000	$ 1,600,000
Available-for-sale securities, realized loss	1,600,000	300,000	500,000
Unrealized loss related to equity securities	6,000,000
Available-for-sale marketable securities, Fair Market Value of Investments in debt securities with Unrealized Losses	191,978,000	1,350,896,000
Fair market value of investments with unrealized losses greater than one year	28,500,000	141,000,000
Aggregate loss of investments with unrealized losses greater than one year	1,600,000	1,200,000
Fair market value of investments with unrealized losses less than one year	163,500,000	1,209,900,000
Aggregate loss of investments with unrealized losses less than one year	1,400,000	2,200,000
Unrealized Gain (loss) on contracts	$ 2,400,000	$ (2,900,000)	$ 8,000,000
Accounts Receivable | Customer 1 | Minimum
Financial Instruments and Fair Value [Line Items]
Concentration risk, percentage	10.00%
Accounts Receivable | Customer 2 | Minimum
Financial Instruments and Fair Value [Line Items]
Concentration risk, percentage		10.00%
Debt Mutual Funds
Financial Instruments and Fair Value [Line Items]
Available-for-sale marketable securities, Fair Market Value of Investments in debt securities with Unrealized Losses	$ 0
Available for sale securities with out contractual maturity date	3,200,000
Mobile Industrial Robots (MiR)
Financial Instruments and Fair Value [Line Items]
Maximum amount of contingent consideration paid for acquisition	115,000,000
Foreign Exchange Contracts
Financial Instruments and Fair Value [Line Items]
Unrealized Gain (loss) on contracts	$ (400,000)	$ (100,000)

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Amount of unrealized loss before deducting unrealized gain on investments in available-for-sale equity securities.

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