INCOME TAXES - Loss carryforwards (Details) $ in Millions	Dec. 31, 2019 USD ($)
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Valuation Allowance	$ 2.3
indemnification receivable	15.0
Capital Loss Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Amount	57.1
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	265.8
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	538.1
Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 254.7

The amount of indemnification receivable.

No definition available.

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Namespace Prefix:	gsah_
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Balance Type:	credit
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- Definition

Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32559-109319

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of valuation allowance pertaining to the deferred tax asset representing potential future taxable deductions from tax credit carryforwards for which it is more likely than not that a tax benefit will not be realized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319

+ Details

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- Details

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