Contract Assets and Liabilities - Summary of assets and liabilities (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Contractors [Line Items]
Contract assets	$ 238,492		$ 160,281
Contract liabilities	(77,293)		(58,534)
Net contract assets (liabilities)	161,199		$ 101,747
Changes in contract assets	38,910	$ 40,179
Net Period Change [Member]
Contractors [Line Items]
Changes in contract assets	78,211
Changes in contract liabilities	(18,759)
Changes in net contract assets (liabilities)	$ 59,452

n/a

No definition available.

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The amount of increase(decrease)in net contract assets(liabilities) during the year.

+ References

No definition available.

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The amount of net contract assets(liabilities) as at balance sheet period.

+ References

No definition available.

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- 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, classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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-SubTopic 10
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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130531-203044

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Amount of increase (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.

+ References

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-Publisher FASB
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The change during the period, either increase or decrease, in amounts payable to customers. The term customers generally excludes other broker-dealers; persons who are principal officers, directors, and stockholders; and persons whose securities or funds are part of the regulatory net capital of the broker-dealer. Another broker-dealer's account can be classified as a customer if the account is carried as an omnibus account in compliance with certain regulations. The accounts of principal officers, directors and stockholders may be combined in the customer captions if they are not material and the combination is disclosed in the oath that is required to accompany the annual audited FOCUS Report.

+ References

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