Intangible Assets - Summary of Changes in Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Intangible Assets Net Excluding Goodwill [Abstract]
Balance at beginning of the period	$ 6,654	$ 7,050	$ 7,217	$ 7,625
Amortization of intangible assets	(69)	(295)	(444)	(852)
Other, primarily impact from changes in foreign currency exchange rates	(148)	260	(336)	242
Balance at end of the period	$ 6,437	$ 7,015	$ 6,437	$ 7,015

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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