Commitments and Contingencies (Guarantees - Demerger and Divesture Obligations Narrative) (Details) € in Millions, $ in Millions	248 Months Ended
	Jun. 30, 2020 USD ($)	Sep. 30, 2020 EUR (€)	Sep. 30, 2020 USD ($)
Indemnification Agreements Hoechst [Member]
Loss Contingencies [Line Items]
Number of divestiture agreements		19	19
Indemnification amount | €		€ 250
Indemnification ceiling amount | €		€ 750
Indemnification percentage exceeding ceiling amount		33.33%	33.33%
Loss contingency accrual, carrying value, payments | $	$ 95
Indemnification percentage, other		33.33%	33.33%
Divestiture Agreements [Member]
Loss Contingencies [Line Items]
Guarantor obligations, maximum exposure | $			$ 116