XML 89 R39.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Accounting Policies (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2019
Accounting Policies [Abstract] |
Schedule of Property, Plant and Equipment Useful Lives | Land is not depreciated. Depreciation on fixed assets is computed using the straight-line method over their estimated useful lives, as follows:
Buildings |  | 33 years
Facilities and leasehold improvements |  | 5-10 years
Machinery and equipment |  | 2-10 years
Computer and R&D equipment |  | 3-6 years
Other |  | 2-5 years

X
- Definition Schedule Of Property Plant And Equipment Useful Lives Table [Text Block] + References No definition available. + Details
Name: | stm_ScheduleOfPropertyPlantAndEquipmentUsefulLivesTableTextBlock
Namespace Prefix: | stm_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

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