Revenue from Contracts with Customers - Contract Balances (Details) - USD ($)	9 Months Ended
Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Contract with Customer [Line Items]
Contract assets	$ 2,848,000	$ 7,120,000	$ 0
Deferred revenue and customer advances	6,446,000	5,906,000	$ 5,342,000
Revenue recognized from deferred revenue	3,100,000
Amount of contract assets reclassified to receivables	7,100,000
Capitalized contract costs	1,300,000
Impairment	0
Satisfied in Previous Period
Contract with Customer [Line Items]
Revenue recognized from deferred revenue	0
Other long-term liabilities
Contract with Customer [Line Items]
Deferred revenue, included in other long-term liabilities	$ 399,000	$ 341,000

[Line Items] for Contract with Customer [Table]

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- Definition

Amount of impairment loss for asset recognized from cost incurred to obtain or fulfill contract with customer.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 40
-Section 50
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Amount, after accumulated amortization and accumulated impairment loss, of asset recognized from cost incurred to obtain or fulfill contract with customer.

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Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time, classified as current.

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Amount of decrease in right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time from transfer to receivable due to right to consideration becoming unconditional.

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- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as current.

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Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as noncurrent.

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Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

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