Venezuela	3 Months Ended
Dec. 31, 2017
Equity Method Investments And Joint Ventures [Abstract]
Venezuela	N. Venezuela Cabot owns 49% of a carbon black operating affiliate in Venezuela, which is accounted for as an equity affiliate, through wholly-owned subsidiaries that carry the investment and receive its dividends. As of December 31, 2017, these subsidiaries carried the operating affiliate investment of $14 million. During the three months ended December 31, 2017 and 2016, the Company received dividends in the amounts of $2 million and $1 million, respectively, which were paid in U.S. dollars. A significant portion of the Company’s operating affiliate’s sales are exports denominated in U.S. dollars. The Venezuelan government mandates that a certain percentage of the dollars collected from these sales be converted into bolivars. The exchange rate made available to the Company as of December 31, 2017 was 3,345 bolivars to the U.S. dollar, which was unchanged from the exchange rate available to the Company as of September 30, 2017. The operating entity has generally been profitable. The Company continues to closely monitor developments in Venezuela and their potential impact on the recoverability of its equity affiliate investment. Any future change in the exchange rate made available to the Company could cause the Company to change the exchange rate it uses and result in gains or losses on the bolivar denominated assets held by its operating affiliate and wholly-owned subsidiaries.

N. Venezuela

Cabot owns 49% of a carbon black operating affiliate in Venezuela, which is accounted for as an equity affiliate, through wholly-owned subsidiaries that carry the investment and receive its dividends. As of December 31, 2017, these subsidiaries carried the operating affiliate investment of $14 million.

During the three months ended December 31, 2017 and 2016, the Company received dividends in the amounts of $2 million and $1 million, respectively, which were paid in U.S. dollars.

A significant portion of the Company’s operating affiliate’s sales are exports denominated in U.S. dollars. The Venezuelan government mandates that a certain percentage of the dollars collected from these sales be converted into bolivars. The exchange rate made available to the Company as of December 31, 2017 was 3,345 bolivars to the U.S. dollar, which was unchanged from the exchange rate available to the Company as of September 30, 2017.

The operating entity has generally been profitable. The Company continues to closely monitor developments in Venezuela and their potential impact on the recoverability of its equity affiliate investment. Any future change in the exchange rate made available to the Company could cause the Company to change the exchange rate it uses and result in gains or losses on the bolivar denominated assets held by its operating affiliate and wholly-owned subsidiaries.