Intangibles - Amortization of Intangible Assets Acquired (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Capitalized patent costs	$ 9,084	$ 8,757
Intangible assets acquired:
Gross intangible assets	12,354	12,027
Accumulated amortization	(5,655)	(5,378)
Intangibles, net	$ 6,699	6,649
Capitalized Patent Costs [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	17 years
Capitalized Patent Costs [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	20 years
Purchased Patents and Intellectual Property [Member]
Intangible assets acquired:
Intangible assets amount	$ 250	250
Purchased Patents and Intellectual Property [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	3 years
Purchased Patents and Intellectual Property [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	10 years
Existing Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	5 years
Intangible assets acquired:
Intangible assets amount	$ 1,560	1,560
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	7 years
Intangible assets acquired:
Intangible assets amount	$ 290	290
Backlog [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	2 years
Intangible assets acquired:
Intangible assets amount	$ 760	760
Tradenames [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	3 years
Intangible assets acquired:
Intangible assets amount	$ 290	290
Non-solicitation Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	1 year
Intangible assets acquired:
Intangible assets amount	$ 120	$ 120