XML 62 R50.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Subsequent Events (Details) - Subsequent Event - USD ($) $ / shares in Units, $ in Millions | Apr. 26, 2018 | Apr. 23, 2018 | Apr. 19, 2018 | Apr. 12, 2018
--- | --- | --- | --- | ---
Subsequent Event |  |  |  |
Stockholders' Equity Note, Stock Split |  |  |  | 3022259.23
Common stock dividend declared (usd per share) |  | $ 0.0645 |  |
Common stock dividend declared, prorated quarterly (usd per share) |  | 0.085 |  |
Common stock dividend declared, annualized (usd per share) |  | $ 0.34 |  |
IPO |  |  |  |
Subsequent Event |  |  |  |
Percentage of ownership sold in transaction |  | 11.60% |  |
Legal fees |  | $ 3.2 |  |
Common Stock |  |  |  |
Subsequent Event |  |  |  |
Shares issued (shares) | 3,097,525 |  |  |
Shares issued (usd per share) | $ 15 |  |  |
Common Stock | IPO |  |  |  |
Subsequent Event |  |  |  |
Shares issued in IPO (shares) | 38,097,525 | 35,000,000 |  |
Sale price (usd per share) |  | $ 15 |  |
Brookfield |  |  |  |
Subsequent Event |  |  |  |
Dividends, Cash |  |  | $ 160.0 |
Potential distribution of cash savings |  | 85.00% |  |
Ownership interest threshold |  | 25.00% |  |
Potential percentage of voting interest |  | 37.50% |  |
Brookfield | LIBOR |  |  |  |
Subsequent Event |  |  |  |
Margin spread on variable interest rate |  | 1.00% |  |
Brookfield | Brookfield Promissory Note |  |  |  |
Subsequent Event |  |  |  |
Dividends payable |  |  | $ 750.0 |
Brookfield | Brookfield Promissory Note | LIBO |  |  |  |
Subsequent Event |  |  |  |
Margin spread on variable interest rate |  |  | 4.50% |
Brookfield | Brookfield Promissory Note | LIBO | Third Anniversary |  |  |  |
Subsequent Event |  |  |  |
Margin spread on variable interest rate |  |  | 2.00% |
Maximum | Brookfield |  |  |  |
Subsequent Event |  |  |  |
Leverage ratio |  |  | 175.00% |
Maximum | Brookfield | Brookfield Promissory Note |  |  |  |
Subsequent Event |  |  |  |
Leverage ratio |  |  | 175.00% |

X
- Definition Common Stock, Dividends, Per Share, Declared, Annualized + References No definition available. + Details
Name: | gti_CommonStockDividendsPerShareDeclaredAnnualized
Namespace Prefix: | gti_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Common Stock, Dividends, Per Share, Declared, Prorated Quarterly + References No definition available. + Details
Name: | gti_CommonStockDividendsPerShareDeclaredProratedQuarterly
Namespace Prefix: | gti_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Ownership Interest Threshold + References No definition available. + Details
Name: | gti_OwnershipInterestThreshold
Namespace Prefix: | gti_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Potential Distribution of Tax Savings, Percentage + References No definition available. + Details
Name: | gti_PotentialDistributionofTaxSavingsPercentage
Namespace Prefix: | gti_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Potential Percentage of Voting Interest + References No definition available. + Details
Name: | gti_PotentialPercentageofVotingInterest
Namespace Prefix: | gti_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Sale of Stock, Percentage of Ownership Sold in Transaction + References No definition available. + Details
Name: | gti_SaleofStockPercentageofOwnershipSoldinTransaction
Namespace Prefix: | gti_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Aggregate dividends declared during the period for each share of common stock outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
Name: | us-gaap_CommonStockDividendsPerShareDeclared
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of paid and unpaid cash dividends declared for classes of stock, for example, but not limited to, common and preferred. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 405 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6957935&loc=d3e64057-112817 + Details
Name: | us-gaap_DividendsCash
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(15)(5)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(24)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(20)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(15)(5)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
Name: | us-gaap_DividendsPayableCurrentAndNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of expense provided in the period for legal costs incurred on or before the balance sheet date pertaining to resolved, pending or threatened litigation, including arbitration and mediation proceedings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.3) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
Name: | us-gaap_LegalFees
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The number of shares issued or sold by the subsidiary or equity method investee per stock transaction. + References No definition available. + Details
Name: | us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction. + References No definition available. + Details
Name: | us-gaap_SaleOfStockPricePerShare
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of shares of stock issued as of the balance sheet date, including shares that had been issued and were previously outstanding but which are now held in the treasury. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21463-112644 + Details
Name: | us-gaap_SharesIssued
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Per share or per unit amount of equity securities issued. + References No definition available. + Details
Name: | us-gaap_SharesIssuedPricePerShare
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Description of the stock split arrangement. Also provide the retroactive effect given by a stock split that occurs after the balance date but before the release of financial statements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SAB Topic 4.C) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187143-122770 + Details
Name: | us-gaap_StockholdersEquityNoteStockSplit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event. + References No definition available. + Details
Name: | us-gaap_SubsequentEventLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of tier one capital to total leverage exposure, as defined by regulatory framework. + References No definition available. + Details
Name: | us-gaap_SupplementaryLeverageRatio
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=us-gaap_IPOMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_CommonStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CounterpartyNameAxis=gti_BrookfieldMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=gti_BrookfieldPromissoryNoteMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=gti_LIBOMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | gti_AnniversaryAxis=gti_ThirdAnniversaryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |