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Revenue - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Costs in excess of billings	$ 22,634	$ 16,532	$ 16,532
Contract with customer liability	(12,028)		(3,681)
Billings in excess of cost
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with customer liability	(17,857)		(12,779)
Revenue recognized	10,097
Unearned revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with customer liability	(12,028)		$ (3,336)
Revenue recognized	$ 2,988

X

- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
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- Definition

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

+ References

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