Retirement Plans and Other Postretirement Benefits

9 Months Ended

Sep. 30, 2019

Retirement Benefits [Abstract]

Retirement Plans and Other Postretirement Benefits

Retirement Plans and Other Postretirement Benefits

Pinnacle West sponsors a qualified defined benefit and account balance pension plan, a non-qualified supplemental excess benefit retirement plan, and an other postretirement benefit plan for the employees of Pinnacle West and our subsidiaries.  Pinnacle West uses a December 31 measurement date for its pension and other postretirement benefit plans.  The market-related value of our plan assets is their fair value at the measurement dates.

The following table provides details of the plans’ net periodic benefit costs and the portion of these costs charged to expense (including administrative costs and excluding amounts capitalized as overhead construction or billed to electric plant participants) (dollars in thousands):

	Pension Benefits												Other Benefits
	Three Months Ended September 30,						Nine Months Ended September 30,						Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018			2019			2018			2019			2018
Service cost — benefits earned during the period	$	12,476		$	14,167		$	37,427		$	42,501		$	4,593		$	5,275		$	13,777		$	15,825
Non-service costs (credits):
Interest cost on benefit obligation	34,211			31,172			102,632			93,517			7,473			7,037			22,420			21,111
Expected return on plan assets	(42,971		)	(45,713		)	(128,913		)	(137,140		)	(9,603		)	(10,520		)	(28,809		)	(31,561		)
Amortization of:
Prior service credit	—			—			—			—			(9,456		)	(9,461		)	(28,366		)	(28,382		)
Net actuarial loss	10,646			8,021			31,938			24,062			—			—			—			—
Net periodic benefit cost (credit)	$	14,362		$	7,647		$	43,084		$	22,940		$	(6,993	)	$	(7,669	)	$	(20,978	)	$	(23,007	)
Portion of cost (credit) charged to expense	$	7,593		$	2,524		$	22,837		$	7,535		$	(4,966	)	$	(5,359	)	$	(14,846	)	$	(16,083	)

Contributions

We have made voluntary contributions of $150 million to our pension plan year-to-date in 2019. The minimum required contributions for the pension plan are zero for the next three years. We expect to make voluntary contributions up to a total of $350 million during the 2019-2021 period. We do not expect to make any contributions over the next three years to our other postretirement benefit plans. In 2019, the Company was reimbursed $30 million for prior year retiree medical claims from the other postretirement benefit plan trust assets.