Adjustments to additional paid In capital stock issued issuance costs including underwriters fees.

No definition available.

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- Definition

The maximum amount of dissolution expenses allowed in the event a Business Combination is not completed in accordance with conditions stated.

+ References

No definition available.

+ Details

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- Definition

Percentage of shares the company will redeem if business combination is not completed at specified time period.

+ References

No definition available.

+ Details

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- Definition

Redemption percentage to allow release of funds held in trust.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
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- Definition

Redemption rights or liquidating distributions with respect to warrants.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Regulatory withdrawal of interest from trust account, maximum period.

+ References

No definition available.

+ Details

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Namespace Prefix:	grsh_
Data Type:	xbrli:durationItemType
Balance Type:	na
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- Definition

Significant accounting policies.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
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- Definition

Threshold net tangible assets for redemption of public shares.

+ References

No definition available.

+ Details

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

- Definition

Threshold number of period in which the public shares are to be redeemed if business combination is not completed within the specified period of time.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
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- Definition

Threshold period from the closing date of the Public Offering to complete its Business Combination.

+ References

No definition available.

+ Details

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Namespace Prefix:	grsh_
Data Type:	xbrli:durationItemType
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- Definition

Underwriters fees.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of working capital for the reporting period.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

The amount of cash, securities, or other assets held by a third-party trustee pursuant to the terms of an agreement which assets are available to be used by beneficiaries to that agreement only within the specific terms thereof and which agreement is expected to terminate more than one year from the balance sheet date (or operating cycle, if longer) at which time the assets held-in-trust will be released or forfeited.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(b))
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Balance Type:	debit
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- Definition

The amount of cash deposited in financial institutions as of the balance sheet date that is insured by the Federal Deposit Insurance Corporation.

+ References

No definition available.

+ Details

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- Definition

Total obligations incurred as part of normal operations that are expected to be paid during the following twelve months or within one business cycle, if longer.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Number of new stock issued during the period.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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Balance Type:	na
Period Type:	duration

- Definition

The number of securities classified as temporary equity that have been sold (or granted) to the entity's shareholders. Securities issued include securities outstanding and securities held in treasury. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with put option held by ESOP and stock redeemable by holder only in the event of a change in control of the issuer.

+ References

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Balance Type:	na
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- Definition

Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32718-109319

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Significant Accounting Policies - Additional Information (Details) - USD ($)		3 Months Ended
	Sep. 11, 2018	Mar. 31, 2019	Dec. 31, 2018
Significant Accounting Policies [Line Items]
Cash balance, federal depository insurance coverage		$ 250,000
Shares subject to possible redemption, issued		38,564,626	38,398,161
Accrued interest and penalties related to unrecognized tax liabilities		$ 0
Investments and cash held in Trust Account	$ 400,000,000	$ 404,963,670	$ 402,605,952
Redemption percentage for release of Trust Account funds		100.00%
Redemption percentage if business combination is not completed		100.00%
Regulatory withdrawal of interest from trust account, maximum period		24 months
Dissolution expenses, maximum allowed		$ 100,000
Redemption rights or liquidating distributions with respect to warrants		0
Current liabilities		784,602	687,370
Working capital		(56,675)	$ 375,661
Maximum
Significant Accounting Policies [Line Items]
Threshold net tangible assets		$ 5,000,001
Number of months to complete business combination		24 months
Regulatory withdrawal of interest from trust account, maximum period		24 months
Number of days to redeem the shares if Business combination is not completed		10 days
Class A Common Stock
Significant Accounting Policies [Line Items]
Shares subject to possible redemption, issued		38,564,626	38,398,161
IPO
Significant Accounting Policies [Line Items]
offering costs including underwriter?s fees	22,756,432
Underwriter's fees	$ 22,000,000
IPO \| Maximum
Significant Accounting Policies [Line Items]
Threshold net tangible assets		$ 5,000,001
IPO \| Class A Common Stock
Significant Accounting Policies [Line Items]
Sale of common stock (in shares)		40,000,000