For an unclassified balance sheet, the amount due from customers or clients for goods or services that have been delivered or sold in the normal course of business, reduced to their estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(9))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(4))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(5))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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Industry and Geographic Information - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016
Revenue, Major Customer [Line Items]
Number of reportable segments \| segment	1
Sales [Member]
Revenue, Major Customer [Line Items]
Percentage of risk concentration by major customer	10.00%
Customer Concentration Risk [Member] \| Sales [Member]
Revenue, Major Customer [Line Items]
Percentage of risk concentration by major customer	44.00%	54.00%	44.00%
Customer Concentration Risk [Member] \| Sales [Member] \| Non-US [Member]
Revenue, Major Customer [Line Items]
Percentage of risk concentration by major customer	32.00%	18.00%	17.00%
Geographic Concentration Risk [Member] \| Non-US [Member]
Revenue, Major Customer [Line Items]
Accounts receivable	$ 23.4	$ 18.8
Credit Concentration Risk [Member]
Revenue, Major Customer [Line Items]
Accounts receivable	$ 33.3	$ 44.4
Credit Concentration Risk [Member] \| Accounts Receivable [Member] \| Minimum [Member]
Revenue, Major Customer [Line Items]
Percentage of risk concentration by major customer	10.00%	10.00%