| **Basis of Presentation and Significant Accounting Policies - Accrued Rebates and Other Accruals (Details) - USD ($) $ in Millions** | Mar. 29, 2020 | Dec. 31, 2019 |
|--------------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|
| **Schedule Of Accrued Liabilities [Line Items]**                                                                                     |          |          |
| Accrued rebates and other accruals                                                                                                   | $ 5,645       | $ 5,689       |
| Trade accounts receivable, less allowance for doubtful accounts [Member]                                                             |          |          |
| **Schedule Of Accrued Liabilities [Line Items]**                                                                                     |          |          |
| Accrued rebates and other accruals                                                                                                   | 1,107         | 1,257         |
| Other current liabilities [Member]                                                                                                   |          |          |
| **Schedule Of Accrued Liabilities [Line Items]**                                                                                     |          |          |
| Accrued rebates                                                                                                                      | 3,408         | 3,285         |
| Other accruals                                                                                                                       | 553           | 581           |
| Other noncurrent liabilities [Member]                                                                                                |          |          |
| **Schedule Of Accrued Liabilities [Line Items]**                                                                                     |          |          |
| Accrued rebates and other accruals                                                                                                   | $ 577         | $ 565         |

| X                                                                                                                                                                                                                  |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Accrued Rebates
+ References
No definition available.
+ Details**Name:**pfe_AccruedRebates**Namespace Prefix:**pfe_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Other Accruals
+ References
No definition available.
+ Details**Name:**pfe_OtherAccruals**Namespace Prefix:**pfe_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                   |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Medicare rebates, Medicaid and related state program rebates, performance-based contract rebates, chargebacks, sales allowances and sales returns and cash discounts
+ References
No definition available.
+ Details**Name:**pfe_RebatesAndDiscountsAccrual**Namespace Prefix:**pfe_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
[Line Items] for Schedule Of Accrued Liabilities [Table]
+ References
No definition available.
+ Details**Name:**pfe_ScheduleOfAccruedLiabilitiesLineItems**Namespace Prefix:**pfe_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                         |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_BalanceSheetLocationAxis=us-gaap_AccountsReceivableMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_BalanceSheetLocationAxis=us-gaap_OtherCurrentLiabilitiesMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                 |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_BalanceSheetLocationAxis=us-gaap_OtherNoncurrentLiabilitiesMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |