Revenue Recognition - Additional Information (Detail) - Topic 606 [Member] - USD ($)	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2017
Summary Of Accounting Policies [Line Items]
Cumulative-effect adjustment to retained earnings			$ 404,000
Asset impairment charges related to contract assets	$ 0
Amortization of contract acquisition costs	80,000	$ 141,000
Impairment loss in relation to costs capitalized	$ 0	$ 0

Summary of accounting policies.

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Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 45
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Amount of amortization expense for asset recognized from cost incurred to obtain or fulfill contract with customer.

+ References

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-Publisher FASB
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-Topic 340
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Amount of impairment loss for asset recognized from cost incurred to obtain or fulfill contract with customer.

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Amount of cumulative effect of the change in accounting principle or new accounting pronouncement on retained earnings or other components of equity or net assets in the statement of financial position as of the beginning of the earliest period presented.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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