Postretirement Benefits

Defined Benefit Plans

We provide postretirement benefits to a substantial portion of our employees and retirees. Costs associated with postretirement benefits include pension and postretirement health care expenses for employees, retirees, surviving spouses and dependents.

Generally, the pension plans are non-contributory. Our policy is to fund the pension plans in accordance with applicable U.S. and Canadian government regulations and to make additional contributions from time to time. For the three months ended January 31, 2016 and 2015, we contributed $19 million and $30 million, respectively, to our pension plans to meet regulatory funding requirements. We expect to contribute approximately $80 million to our pension plans during the remainder of 2016.

We primarily fund other post-employment benefit ("OPEB") obligations, such as retiree medical, in accordance with a 1993 Settlement Agreement (the "1993 Settlement Agreement"), which requires us to fund a portion of the plans' annual service cost to a retiree benefit trust (the "Base Trust"). The 1993 Settlement Agreement resolved a class action lawsuit originally filed in 1992 regarding the restructuring of our then applicable retiree health care and life insurance benefits. Contributions for the three months ended January 31, 2016 and 2015, as well as anticipated contributions for the remainder of 2016, are not material.

Components of Net Periodic Benefit Expense

Net periodic benefit expense included in our Consolidated Statements of Operations is comprised of the following:



	Three Months Ended January 31,
	Pension Benefits						Health and Life Insurance Benefits
(in millions)	2016			2015			2016			2015
Service cost for benefits earned during the period	$	2		$	3		$	1		$	1
Interest on obligation	30			36			15			18
Amortization of cumulative loss	26			25			8			10
Amortization of prior service benefit	—			—			—			(1		)
Premiums on pension insurance	4			1			—			—
Expected return on assets	(42		)	(49		)	(6		)	(7		)
Net periodic benefit expense	$	20		$	16		$	18		$	21

In 2016, we changed the approach utilized to estimate the service cost and interest cost components of net periodic benefit cost for our major defined benefit postretirement plans. Historically, we estimated the service cost and interest cost components using a single weighted average discount rate derived from the yield curve used to measure the benefit obligation at the beginning of the period. In 2016, we are using a spot rate approach for the estimation of service and interest cost for our major plans by applying specific spot rates along the yield curve to the relevant projected cash flows, to provide a better estimate of service and interest costs. Interest on the obligation as reported above is $9 million and $4 million lower in the current quarter for pension and for health and life insurance, respectively, as a result of using the spot rate approach compared to the historical approach.

Defined Contribution Plans and Other Contractual Arrangements

Our defined contribution plans cover a substantial portion of domestic salaried employees and certain domestic represented employees. The defined contribution plans contain a 401(k) feature and provide most participants with a matching contribution from the Company. We deposit the matching contribution annually. Many participants covered by the plans receive annual Company contributions to their retirement accounts based on an age-weighted percentage of the participant's eligible compensation for the calendar year. Defined contribution expense pursuant to these plans was $7 million and $9 million in the three months ended January 31, 2016 and 2015, respectively.

In accordance with the 1993 Settlement Agreement, an independent Retiree Supplemental Benefit Trust (the "Supplemental Trust") was established. The Supplemental Trust, and the benefits it provides to certain retirees pursuant to a certain Retiree Supplemental Benefit Program under the 1993 Settlement Agreement ("Supplemental Benefit Program"), is not part of our consolidated financial statements.

Our contingent profit sharing obligations under a certain Supplemental Benefit Trust Profit Sharing Plan ("Supplemental Benefit Trust Profit Sharing Plan") will continue until certain funding targets defined by the 1993 Settlement Agreement are met. We have recorded no profit sharing accruals based on the operating performance of the entities that are included in the determination of qualifying profits. For more information on pending arbitration regarding the Supplemental Benefit Trust Profit Sharing Plan, see Note 11, Commitments and Contingencies.