Accumulated Other Comprehensive Income (Loss) (Tables)

12 Months Ended

Sep. 30, 2017

Changes in Each Component of AOCI, Net of Tax

Changes in each component of AOCI, net of tax, are as follows for fiscal 2016 and 2017:

	Currency Translation Adjustment			Unrealized Gains on Investment		Pension and Other Postretirement Benefit Liability Adjustment			Total
	(In millions)
Balance at September 30, 2015 attributable to Cabot Corporation	$	(239	)	$	2	$	(62	)	$	(299	)
Other comprehensive income (loss)		7			—		(38	)		(31	)
Less: Other comprehensive income (loss) attributable to noncontrolling interests		(5	)		—		—			(5	)
Balance at September 30, 2016 attributable to Cabot Corporation		(227	)		2		(100	)		(325	)
Other comprehensive income (loss) before reclassifications		25			—		41			66
Amounts reclassified from AOCI		—			—		2			2
Less: Other comprehensive income (loss) attributable to noncontrolling interests		2			—		—			2
Balance at September 30, 2017 attributable to Cabot Corporation	$	(204	)	$	2	$	(57	)	$	(259	)

Amounts Reclassified Out of AOCI

The amounts reclassified out of AOCI and into the Consolidated Statements of Operations for the fiscal year ended September 30, 2017, 2016 and 2015 are as follows:

	Affected Line Item in the Consolidated	September 30
	Statements of Operations	2017			2016			2015
		(In Millions)
Pension and other postretirement benefit liability adjustment
Amortization of actuarial losses (gains)	Net Periodic Benefit Cost - see Note L for details	$	5		$	3		$	(1	)
Amortization of prior service (credit) cost	Net Periodic Benefit Cost - see Note L for details		(3	)		(3	)		4
Settlement and curtailment (credit) cost	Net Periodic Benefit Cost - see Note L for details		—			—			27
Total before tax			2			—			30
Tax impact	Provision for income taxes		—			—			(6	)
Total after tax		$	2		$	—		$	24