Stock Plans (Additional Information) (Details) - shares	Sep. 30, 2021	May 31, 2017
2017 Performance Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated common stock to be awarded under a stock benefit plan, maximum limit (in shares)		25,000,000
Shares available for grant under the plan (in shares)	14,833,501
Non Employee Directors Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated common stock to be awarded under a stock benefit plan, maximum limit (in shares)		1,000,000
Shares available for grant under the plan (in shares)	914,413
Percentage of voting shares that PMI may own, used in determining non-employee director status		50.00%