Significant Accounting Policies (Detail)	3 Months Ended
	Mar. 31, 2019 USD ($) Project Method Source $ / shares shares	Mar. 31, 2018 USD ($) Project	Feb. 26, 2019 USD ($)	Dec. 31, 2018 USD ($)
Accounting Policies [Line Items]
Number of product revenue sources | Method	2
Unbilled receivables	$ 66,700,000			$ 57,000,000
Number of projects | Project	21	8
Percentage of total revenues	18.00%	11.00%
Percentage of product revenues	26.00%	16.00%
Number of service revenue sources | Source	2
Severance costs	$ 2,400,000
Treasury stock shares (in shares) | shares	28,078,000
Average price of shares (in dollars per share) | $ / shares	$ 39.74
Reclassified from engineering cost to product development cost		$ 5,000,000
Reclassified from selling general and administrative cost to product cost of sales		$ 700,000
Engineering cost	$ 4,200,000
Quality assurance cost	$ 800,000
Common Stock
Accounting Policies [Line Items]
Shares authorized to be purchased (up to) (in shares)			$ 100,000,000
Treasury stock shares (in shares) | shares	28,078
Treasury stock, value of acquired shares	$ 1,100,000