Commitments and Contingencies (Guarantees - Demerger and Divesture Obligations Narrative) (Details) € in Millions, $ in Millions	12 Months Ended	218 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2017 EUR (€)
Indemnification Agreements Hoechst [Member]
Loss Contingencies [Line Items]
Number of divestiture agreements	19	19	19
Indemnification floor amount | €			€ 250
Indemnification ceiling amount | €			€ 750
Indemnification percentage exceeding ceiling amount	33.33%	33.33%	33.33%
Loss contingency accrual, carrying value, payments | $		$ 80
Indemnification percentage, other	33.33%	33.33%	33.33%
Divestiture Agreements [Member]
Loss Contingencies [Line Items]
Divestiture obligations range, years	2037
Guarantee obligations, maximum exposure | $	$ 122	$ 122