Goodwill and Other Intangible Assets (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Goodwill, Impairment Loss			$ 6,500		$ 6,500
Goodwill, Gross	$ 8,400		8,400		$ 8,200
Amortization of intangibles	27	$ 18	68	$ 53
Finite-Lived Intangible Assets, Amortization Expense, 2019	112		112
Finite-Lived Intangible Assets, Amortization Expense, 2020	111		111
Finite-Lived Intangible Assets, Amortization Expense, 2021	110		110
Finite-Lived Intangible Assets, Amortization Expense, 2022	110		110
Finite-Lived Intangible Assets, Amortization Expense, 2023	$ 109		109
3M Communications Market Division [Member]
Finite-lived Intangible Assets Acquired			511
Amortization of intangibles			68
Finite Lived Intangible Assets, Foreign Currency Translation Gain (Loss)			10
Other Acquisition [Member]
Finite-lived Intangible Assets Acquired			$ 7