RETIREMENT BENEFITS AND TRUSTEED ASSETS

The following table details the components of net periodic benefit costs for pension benefits and other postretirement benefits:



	Pension						Other Postretirement
	Benefits						Benefits
	2013			2012			2013			2012
Three Months Ended June 30	(In millions)
Service cost	$	25		$	20		$	12		$	18
Interest cost	47			51			21			31
Expected return on plan assets	(66		)	(61		)	(27		)	(23		)
Amortization of:
Net actuarial loss	50			43			15			20
Prior service credit	—			—			(36		)	(7		)
Net periodic benefit cost	$	56		$	53		$	(15	)	$	39



	Pension						Other Postretirement
	Benefits						Benefits
	2013			2012			2013			2012
Six Months Ended June 30	(In millions)
Service cost	$	49		$	41		$	28		$	36
Interest cost	95			102			45			61
Expected return on plan assets	(133		)	(122		)	(54		)	(46		)
Amortization of:
Net actuarial loss	101			85			32			39
Prior service credit	—			—			(59		)	(14		)
Net transition liability	—			—			—			1
Settlements	—			2			—			—
Net periodic benefit cost	$	112		$	108		$	(8	)	$	77

Pension and Other Postretirement Contributions

During the first six months of 2013, the Company contributed $150 million to its pension plans, including a contribution of DTE Energy common stock of $100 million. See Note 8. At the discretion of management, and depending upon financial market conditions, the Company may make up to an additional $125 million contribution to its pension plans in 2013.

In January 2013, the Company contributed $145 million to its other postretirement benefit plans. At the discretion of management, the Company may make up to an additional $120 million contribution to its other postretirement benefit plans in 2013.

Re-Measurement of Other Postretirement Benefit Obligation

In March 2013, the Company reached agreements on new four-year labor contracts with certain represented employees under several bargaining units. As a term of the agreements, the Company replaced sponsored retiree medical, prescription drug and dental coverage for future Medicare eligible retirees with a Retiree Health Care Allowance (RHCA) account of $3,250 per year. The modification in retiree health coverage will reduce future postretirement benefit costs.

Based on the impact of such benefit cost savings on the financial statements, the Company re-measured its retiree health plan as of March 31, 2013. In performing the re-measurement, the Company updated its significant actuarial assumptions, including an adjustment to the discount rate from 4.15% at December 31, 2012 to 4.30% at March 31, 2013. Plan assets were also updated to reflect fair value as of the re-measurement date. As a result of the re-measurement, the accumulated postretirement benefit obligation (ABPO) was reduced by $258 million. The Company's Accrued postretirement benefit liability at March 31, 2013 was $721 million as compared to $1.2 billion at December 31, 2012, a reduction of $439 million. The reduction reflects the impact of the re-measurement of the plan, January 2013 plan contributions and recognition of first quarter 2013 postretirement benefit costs and benefit payments.

Beginning April 2013, net postretirement benefit costs were recorded based on the updated actuarial assumptions and benefit changes resulting from the new labor contracts. As a result of the re-measurement, fiscal year 2013 postretirement benefit costs are expected to decrease by approximately $69 million to an annual net benefit of approximately $40 million.