Contract Assets and Contract Liabilities - Changes in Contract Assets and Liabilities (Details)	6 Months Ended
Jun. 30, 2019 USD ($)
Revenue From Contract With Customer [Abstract]
Cumulative adjustment due to changes in contract values	$ 1,792,183
Cumulative adjustment due to changes in estimated costs at completion	(2,788,666)
Revenue recognized in the period	60,167,437
Amounts reclassified to receivables	(56,002,387)
Impairment of contract assets	51,708
Total	$ 3,220,275

Contract with customer asset impairment.

No definition available.

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Namespace Prefix:	gv_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Increase (Decrease) In Net Contract Assets (Liabilities)

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Definition

Amount of increase (decrease) in revenue recognized for cumulative catch-up adjustment from contract modification which increases (decreases) 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 50
-Paragraph 10
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130551-203045

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130551-203045

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of increase (decrease) in revenue recognized for cumulative catch-up adjustment from change in estimate of transaction price which (increases) decreases obligation to transfer good or service to customer for which consideration from customer has been received or is due. Includes, but is not limited to, change in assessment of whether estimate of variable consideration is constrained.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

+ Details

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Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

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