XML 70 R29.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Foreign Operations | 12 Months Ended
--- | ---
Dec. 31, 2024
Concentration Risks, Types, No Concentration Percentage [Abstract] |
Foreign Operations | Foreign Operations For the years ended December 31, 2024, 2023, and 2022, we did not derive revenues in excess of 10% of our consolidated revenues from any one foreign country. At December 31, 2024 and December 31, 2023, the United Kingdom was the only foreign country that held more than 10% of our identifiable assets. The following table shows our domestic and foreign revenues and identifiable assets for the years ended or as of December 31 (in millions):
| 2024 |  | 2023 |  | 2022
Revenues |  |  |  |  |
Foreign | $ | 637.3 |  |  | $ | 548.1 |  |  | $ | 466.9 |
United States | 948.2 |  |  | 862.8 |  |  | 806.1 |
Total | $ | 1,585.5 |  |  | $ | 1,410.9 |  |  | $ | 1,273.0 |
Identifiable Assets |  |  |  |  |
Foreign | $ | 5,167.2 |  |  | $ | 4,718.5 |  |  | $ | 3,910.2 |
United States | 7,129.3 |  |  | 6,607.5 |  |  | 6,161.8 |
Total | $ | 12,296.5 |  |  | $ | 11,326.0 |  |  | $ | 10,072.0 |

X
- Definition Concentration Risk Geographic. + References No definition available. + Details
Name: | gmt_ConcentrationRiskGeographicTextBlock
Namespace Prefix: | gmt_
Data Type: | dtr-types1:textBlockItemType
Balance Type: | na
Period Type: | duration

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