Accumulated Other Comprehensive Income (Loss) (Tables)

6 Months Ended

Mar. 31, 2019

Changes in Each Component of AOCI, Net of Tax

Changes in each component of AOCI, net of tax, were as follows:

	Currency Translation Adjustment			Unrealized Gains on Investments		Pension and Other Postretirement Benefit Liability Adjustments			Total
	(In millions)
Balance at September 30, 2018, attributable to Cabot Corporation	$	(266	)	$	1	$	(52	)	$	(317	)
Other comprehensive income (loss) before reclassifications		(24	)		—		30			6
Amounts reclassified from AOCI		(1	)		—		(8	)		(9	)
Less: Other comprehensive income (loss) attributable to noncontrolling interests		—			—		—			—
Balance at December 31, 2018, attributable to Cabot Corporation	$	(291	)	$	1	$	(30	)	$	(320	)
Other comprehensive income (loss) before reclassifications		8			—		1			9
Amounts reclassified from AOCI		(1	)		—		(1	)		(2	)
Less: Other comprehensive income (loss) attributable to noncontrolling interests		2			—		—			2
Balance at March 31, 2019, attributable to Cabot Corporation		(286	)		1		(30	)		(315	)

Amounts Reclassified Out of AOCI

The amounts reclassified out of AOCI and into the Consolidated Statements of Operations in the three and six months ended March 31, 2019 and 2018 were as follows:

	Affected Line Item in the Consolidated	Three Months Ended March 31						Six Months Ended March 31
	Statements of Operations	2019			2018			2019			2018
		(In millions)
Derivatives: net investment hedges
(Gains) losses reclassified to interest expense	Interest expense	$	(2	)	$	(1	)	$	(3	)	$	(2	)
(Gains) losses excluded from effectiveness testing and amortized to interest expense	Interest expense	$	1		$	—		$	1		$	—
Pension and other postretirement benefit liability adjustment
Amortization of actuarial losses	Net Periodic Benefit Cost - see Note E for details		—			—			1			1
Amortization of prior service credit	Net Periodic Benefit Cost - see Note E for details		(1	)		—			(1	)		(1	)
Settlement and curtailment gain	Net Periodic Benefit Cost - see Note E for details		—			—			(6	)		—
Total before tax			(2	)		(1	)		(8	)		(2	)
Tax impact	Provision (benefit) for income taxes		—			—			(3	)		—
Total after tax		$	(2	)	$	(1	)	$	(11	)	$	(2	)