Revenue Recognition - Summary of assets and liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Contract assets	$ 160,281	$ 120,992
Contract liabilities	(58,534)	(30,224)
Net contract assets (liabilities)	101,747	90,768
Changes in contract assets	28,141	$ 17,857	$ 22,013
Net Period Change [Member]
Changes in contract assets	39,289
Changes in contract liabilities	(28,310)
Changes in net contract assets (liabilities)	$ 10,979

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

No definition available.

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- Definition

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

+ References

No definition available.

+ Details

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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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130531-203044

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130533-203044

+ Details

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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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 2
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

+ Details

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- Definition

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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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- Definition

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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