Note 8 - Income Tax (Details Textual) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of geographical areas [line items]
After tax effect of expense not deductible in determining profit (loss)	$ 61	$ 66	$ 65
Charge related to withholding taxes for intra group international operations	$ 10	$ 34	$ 26

The amount represents the difference between the after tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that relates to expenses not deductible in determining profit (loss).

No definition available.

Name:	ts_AfterTaxEffectOfExpenseNotDeductibleInDeterminingProfitLoss
Namespace Prefix:	ts_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration