XML 64 R29.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Interest Expense (Tables) | 6 Months Ended | 12 Months Ended
--- | --- | ---
Jun. 30, 2018 | Dec. 31, 2017
Interest and Debt Expense [Abstract] |  |
Schedule Of Interest Expense | The following tables present the components of interest expense:
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
|  | For the six months ended June 30, |
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
|  | 2018 |  | 2017 |
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
(Dollars in thousands) |
Interest incurred on debt |  | $ | 35,473 |  | $ | 12,086 |
Related party Promissory Note interest expense |  |  | 5,090 |  |  | — |
Senior Note redemption premium |  |  | 4,782 |  |  | — |
Accretion of fair value adjustment on Senior Notes |  |  | 19,414 |  |  | 3,208 |
Accretion of original issue discount on 2018 Term Loans |  |  | 357 |  |  | — |
Amortization of debt issuance costs |  |  | 1,416 |  |  | 154 |
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Total interest expense |  | $ | 66,532 |  | $ | 15,448 |
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
|  | Successor |  | Predecessor |
|  | For the year ended December 31, 2017 |  | For the year ended December 31, 2016 |  | For the period August 15 through December 31, 2015 |  | For the period January 1 through August 14, 2015 |
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
|  | (Dollars in thousands) |
Interest incurred on debt |  | $ | 24,060 |  | $ | 20,408 |  | $ | 7,694 |  | $ | 12,066 |
Amortization of discount on Senior Subordinated Notes |  | — |  | — |  | — |  | 12,027 |
Accretion of fair value adjustment on Senior Notes |  | 6,454 |  | 6,305 |  | 2,305 |  | — |
Amortization of debt issuance costs |  | 309 |  | 201 |  | — |  | 2,118 |
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Total interest expense |  | $ | 30,823 |  | $ | 26,914 |  | $ | 9,999 |  | $ | 26,211 |
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​

X
- Definition Schedule of Interest Expense [Table Text Block] + References No definition available. + Details
Name: | gti_ScheduleOfInterestExpenseTableTextBlock
Namespace Prefix: | gti_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_InterestAndDebtExpenseAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration