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Retirement Plans and Other Benefits | 12 Months Ended
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Dec. 31, 2017
Retirement Benefits [Abstract] |
Retirement Plans and Other Benefits | Retirement Plans and Other Postretirement Benefits Pinnacle West sponsors a qualified defined benefit and account balance pension plan (The Pinnacle West Capital Corporation Retirement Plan) and a non-qualified supplemental excess benefit retirement plan for the employees of Pinnacle West and its subsidiaries. All new employees participate in the account balance plan. Defined benefit plans specify the amount of benefits a plan participant is to receive using information about the participant. The pension plan covers nearly all employees. The supplemental excess benefit retirement plan covers officers of the Company and highly compensated employees designated for participation by the Board of Directors. Our employees do not contribute to the plans. We calculate the benefits based on age, years of service and pay. Pinnacle West also sponsors other postretirement benefit plans (Pinnacle West Capital Corporation Group Life and Medical Plan and Pinnacle West Capital Corporation Post-65 Retiree Health Reimbursement Arrangement) for the employees of Pinnacle West and its subsidiaries. These plans provide medical and life insurance benefits to retired employees. Employees must retire to become eligible for these retirement benefits, which are based on years of service and age. For the medical insurance plan, retirees make contributions to cover a portion of the plan costs. For the life insurance plan, retirees do not make contributions. We retain the right to change or eliminate these benefits. On September 30, 2014, Pinnacle West announced plan design changes to the postretirement benefit plan, which required an interim remeasurement of the benefit obligation for the plan. Effective January 1, 2015, those eligible retirees and dependents over age 65 and on Medicare can choose to be enrolled in a Health Reimbursement Arrangement ("HRA"). The Company is providing a subsidy allowing post-65 retirees to purchase a Medicare supplement plan on a private exchange network. The remeasurement of the benefit obligation included updating the assumptions. The 2014 remeasurement also resulted in a decrease in Pinnacle West’s other postretirement benefit obligation of $316 million, which was offset by the related regulatory asset and accumulated other comprehensive income. Because of plan changes in September 2014, the Company is currently in the process of seeking IRS approval to move approximately $186 million of other postretirement benefit trust assets into a new trust account to pay for active union employee medical costs. In December 2016, FERC approved a methodology for determining the amount of other postretirement benefit trust assets to transfer into a new trust account to pay for active union employee medical costs. On January 2, 2018, these funds were moved to the new trust account. The Company negotiated a draft Closing Agreement granting tentative approval from the IRS prior to the transfer. Subsequent to the transfer, the Company submitted proof of the transfer to the IRS and expects to execute a final Closing Agreement early in 2018. Per the terms of an order from FERC, the Company must also make an informational filing with FERC. The Company made this FERC filing during February 2018. It is the Company’s understanding that completion of these regulatory requirements will then permit access to the approximately $186 million for the sole purpose of paying active union employee medical benefits. Pinnacle West uses a December 31 measurement date each year for its pension and other postretirement benefit plans. The market-related value of our plan assets is their fair value at the measurement date. See Note 13 for further discussion of how fair values are determined. Due to subjective and complex judgments, which may be required in determining fair values, actual results could differ from the results estimated through the application of these methods. A significant portion of the changes in the actuarial gains and losses of our pension and postretirement plans is attributable to APS and therefore is recoverable in rates. Accordingly, these changes are recorded as a regulatory asset or regulatory liability. In its 2009 retail rate case settlement, APS received approval to defer a portion of pension and other postretirement benefit cost increases incurred in 2011 and 2012. We deferred pension and other postretirement benefit costs of approximately $14 million in 2012 and $11 million in 2011. Pursuant to an ACC regulatory order, we began amortizing the regulatory asset over three years beginning in July 2012. We amortized approximately $5 million in 2015, $8 million in 2014, $8 million in 2013 and $4 million in 2012. 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, billed to electric plant participants or charged to the regulatory asset or liability) (dollars in thousands):
| Pension |  | Other Benefits
| 2017 |  | 2016 |  | 2015 |  | 2017 |  | 2016 |  | 2015
Service cost-benefits earned during the period | $ | 54,858 |  |  | $ | 53,792 |  |  | $ | 59,627 |  |  | $ | 17,119 |  |  | $ | 14,993 |  |  | $ | 16,827 |
Interest cost on benefit obligation | 129,756 |  |  | 131,647 |  |  | 123,983 |  |  | 29,959 |  |  | 29,721 |  |  | 28,102 |
Expected return on plan assets | (174,271 | ) |  | (173,906 | ) |  | (179,231 | ) |  | (53,401 | ) |  | (36,495 | ) |  | (36,855 | )
Amortization of: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Prior service cost (credit) | 81 |  |  | 527 |  |  | 594 |  |  | (37,842 | ) |  | (37,883 | ) |  | (37,968 | )
Net actuarial loss | 47,900 |  |  | 40,717 |  |  | 31,056 |  |  | 5,118 |  |  | 4,589 |  |  | 4,881 |
Net periodic benefit cost | $ | 58,324 |  |  | $ | 52,777 |  |  | $ | 36,029 |  |  | $ | (39,047 | ) |  | $ | (25,075 | ) |  | $ | (25,013 | )
Portion of cost charged to expense | $ | 27,295 |  |  | $ | 26,172 |  |  | $ | 20,036 |  |  | $ | (18,274 | ) |  | $ | (12,435 | ) |  | $ | (10,391 | )
See Note 2 for additional information regarding accounting changes relating to ASU 2017-07, Compensation-Retirement Benefits: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The following table shows the plans’ changes in the benefit obligations and funded status for the years 2017 and 2016 (dollars in thousands):
| Pension |  | Other Benefits
| 2017 |  | 2016 |  | 2017 |  | 2016
Change in Benefit Obligation |  |  |  |  |  |  |  |  |  |  |
Benefit obligation at January 1 | $ | 3,204,462 |  |  | $ | 3,033,803 |  |  | $ | 716,445 |  |  | $ | 647,020 |
Service cost | 54,858 |  |  | 53,792 |  |  | 17,119 |  |  | 14,993 |
Interest cost | 129,756 |  |  | 131,647 |  |  | 29,959 |  |  | 29,721 |
Benefit payments | (166,342 | ) |  | (142,247 | ) |  | (30,144 | ) |  | (26,231 | )
Actuarial loss | 171,452 |  |  | 127,467 |  |  | 20,014 |  |  | 50,942 |
Benefit obligation at December 31 | 3,394,186 |  |  | 3,204,462 |  |  | 753,393 |  |  | 716,445 |
Change in Plan Assets |  |  |  |  |  |  |  |  |  |  |
Fair value of plan assets at January 1 | 2,675,357 |  |  | 2,542,774 |  |  | 882,651 |  |  | 833,017 |
Actual return on plan assets | 428,374 |  |  | 166,408 |  |  | 139,367 |  |  | 63,463 |
Employer contributions | 100,000 |  |  | 100,000 |  |  | 353 |  |  | 819 |
Benefit payments | (146,704 | ) |  | (133,825 | ) |  | — |  |  | (14,648 | )
Fair value of plan assets at December 31 | 3,057,027 |  |  | 2,675,357 |  |  | 1,022,371 |  |  | 882,651 |
Funded Status at December 31 | $ | (337,159 | ) |  | $ | (529,105 | ) |  | $ | 268,978 |  |  | $ | 166,206 |
The following table shows the projected benefit obligation and the accumulated benefit obligation for pension plans with an accumulated obligation in excess of plan assets as of December 31, 2017 and 2016 (dollars in thousands):
| 2017 |  | 2016
Projected benefit obligation | $ | 3,394,186 |  |  | $ | 3,204,462 |
Accumulated benefit obligation | 3,227,233 |  |  | 3,049,406 |
Fair value of plan assets | 3,057,027 |  |  | 2,675,357 |
The following table shows the amounts recognized on the Consolidated Balance Sheets as of December 31, 2017 and 2016 (dollars in thousands):
| Pension |  | Other Benefits
| 2017 |  | 2016 |  | 2017 |  | 2016
Noncurrent asset | $ | — |  |  | $ | — |  |  | $ | 268,978 |  |  | $ | 166,206 |
Current liability | (9,859 | ) |  | (19,795 | ) |  | — |  |  | — |
Noncurrent liability | (327,300 | ) |  | (509,310 | ) |  | — |  |  | — |
Net amount recognized | $ | (337,159 | ) |  | $ | (529,105 | ) |  | $ | 268,978 |  |  | $ | 166,206 |
The following table shows the details related to accumulated other comprehensive loss as of December 31, 2017 and 2016 (dollars in thousands):
| Pension |  | Other Benefits
| 2017 |  | 2016 |  | 2017 |  | 2016
Net actuarial loss | $ | 643,199 |  |  | $ | 773,750 |  |  | $ | 75,439 |  |  | $ | 146,509 |
Prior service cost (credit) | — |  |  | 81 |  |  | (265,575 | ) |  | (303,417 | )
APS’s portion recorded as a regulatory (asset) liability | (576,188 | ) |  | (711,059 | ) |  | 189,627 |  |  | 156,575 |
Income tax expense (benefit) | (24,915 | ) |  | (24,202 | ) |  | 853 |  |  | 833 |
Accumulated other comprehensive loss | $ | 42,096 |  |  | $ | 38,570 |  |  | $ | 344 |  |  | $ | 500 |
The following table shows the estimated amounts that will be amortized from accumulated other comprehensive loss and regulatory assets and liabilities into net periodic benefit cost in 2018 (dollars in thousands):
| Pension |  | Other Benefits
Net actuarial loss | $ | 28,334 |  |  | $ | — |
Prior service credit | — |  |  | (37,842 | )
Total amounts estimated to be amortized from accumulated other comprehensive loss (gain) and regulatory assets (liabilities) in 2018 | $ | 28,334 |  |  | $ | (37,842 | )
The following table shows the weighted-average assumptions used for both the pension and other benefits to determine benefit obligations and net periodic benefit costs:
| Benefit Obligations As of December 31, |  | Benefit Costs For the Years Ended December 31,
| 2017 |  | 2016 |  | 2017 |  | 2016 |  | 2015
Discount rate – pension | 3.65 | % |  | 4.08 | % |  | 4.08 | % |  | 4.37 | % |  | 4.02 | %
Discount rate – other benefits | 3.71 | % |  | 4.17 | % |  | 4.17 | % |  | 4.52 | % |  | 4.14 | %
Rate of compensation increase | 4.00 | % |  | 4.00 | % |  | 4.00 | % |  | 4.00 | % |  | 4.00 | %
Expected long-term return on plan assets - pension | N/A |  |  | N/A |  |  | 6.55 | % |  | 6.90 | % |  | 6.90 | %
Expected long-term return on plan assets - other benefits | N/A |  |  | N/A |  |  | 6.05 | % |  | 4.45 | % |  | 4.45 | %
Initial healthcare cost trend rate (pre-65 participants) | 7.00 | % |  | 7.00 | % |  | 7.00 | % |  | 7.00 | % |  | 7.00 | %
Initial healthcare cost trend rate (post-65 participants) | 4.75 | % |  | 5.00 | % |  | 5.00 | % |  | 5.00 | % |  | 5.00 | %
Ultimate healthcare cost trend rate | 4.75 | % |  | 5.00 | % |  | 5.00 | % |  | 5.00 | % |  | 5.00 | %
Number of years to ultimate trend rate (pre-65 participants) | 8 |  |  | 4 |  |  | 4 |  |  | 4 |  |  | 4 |
In selecting the pretax expected long-term rate of return on plan assets, we consider past performance and economic forecasts for the types of investments held by the plan. For 2018, we are assuming a 6.05% long-term rate of return for pension assets and 5.55% (before tax) for other benefit assets, which we believe is reasonable given our asset allocation in relation to historical and expected performance. In selecting our healthcare trend rates, we consider past performance and forecasts of healthcare costs. A one percentage point change in the assumed initial and ultimate healthcare cost trend rates would have the following effects on our December 31, 2017 amounts (dollars in thousands):
| 1% Increase |  | 1% Decrease
Effect on other postretirement benefits expense, after consideration of amounts capitalized or billed to electric plant participants | $ | 8,424 |  |  | $ | (5,616 | )
Effect on service and interest cost components of net periodic other postretirement benefit costs | 9,145 |  |  | (7,037 | )
Effect on the accumulated other postretirement benefit obligation | 128,203 |  |  | (98,143 | )
Plan Assets The Board of Directors has delegated oversight of the pension and other postretirement benefit plans’ assets to an Investment Management Committee (“Committee”). The Committee has adopted investment policy statements (“IPS”) for the pension and the other postretirement benefit plans’ assets. The investment strategies for these plans include external management of plan assets, and prohibition of investments in Pinnacle West securities. The overall strategy of the pension plan’s IPS is to achieve an adequate level of trust assets relative to the benefit obligations. To achieve this objective, the plan’s investment policy provides for mixes of investments including long-term fixed income assets and return-generating assets. The target allocation between return-generating and long-term fixed income assets is defined in the IPS and is a function of the plan’s funded status. The plan’s funded status is reviewed on at least a monthly basis. Changes in the value of long-term fixed income assets, also known as liability-hedging assets, are intended to offset changes in the benefit obligations due to changes in interest rates. Long-term fixed income assets consist primarily of fixed income debt securities issued by the U.S. Treasury and other government agencies, U.S. Treasury Futures Contracts, and fixed income debt securities issued by corporations. Long-term fixed income assets may also include interest rate swaps, and other instruments. Return-generating assets are intended to provide a reasonable long-term rate of investment return with a prudent level of volatility. Return-generating assets are composed of U.S. equities, international equities, and alternative investments. International equities include investments in both developed and emerging markets. Alternative investments include investments in real estate, private equity and various other strategies. The plan may also hold investments in return-generating assets by holding securities in partnerships, common and collective trusts and mutual funds. Based on the IPS, and given the pension plan's funded status at year-end 2017, the target and actual allocation for the pension plan at December 31, 2017 are as follows:
| Pension
| Target Allocation |  | Actual Allocation
Long-term fixed income assets | 62 | % |  | 58 | %
Return-generating assets | 38 | % |  | 42 | %
Total | 100 | % |  | 100 | %
The permissible range is within +/- 3% of the target allocation shown in the above table, and also considers the Plan's funded status. The following table presents the additional target allocations, as a percent of total pension plan assets, for the return-generating assets:
Asset Class | Target Allocation
Equities in US and other developed markets | 18 | %
Equities in emerging markets | 6 | %
Alternative investments | 14 | %
Total | 38 | %
The pension plan IPS does not provide for a specific mix of long-term fixed income assets, but does expect the average credit quality of such assets to be investment grade. As of December 31, 2017, the asset allocation for other postretirement benefit plan assets is governed by the IPS for those plans, which provides for different asset allocation target mixes depending on the characteristics of the liability. Some of these asset allocation target mixes vary with the plan’s funded status. The following table presents the actual allocations of the investment for the other postretirement benefit plan at December 31, 2017:
| Other Benefits
| Actual Allocation
Long-term fixed income assets | 67 | %
Return-generating assets | 33 | %
Total | 100 | %
See Note 13 for a discussion on the fair value hierarchy and how fair value methodologies are applied. The plans invest directly in fixed income, U.S. Treasury Futures Contracts, and equity securities, in addition to investing indirectly in fixed income securities, equity securities and real estate through the use of mutual funds, partnerships and common and collective trusts. Equity securities held directly by the plans are valued using quoted active market prices from the published exchange on which the equity security trades, and are classified as Level 1. U.S. Treasury Future Contracts are valued using the quoted active market prices from the exchange on which they trade, and are classified as Level 1. Fixed income securities issued by the U.S. Treasury held directly by the plans are valued using quoted active market prices, and are classified as Level 1. Fixed income securities issued by corporations, municipalities, and other agencies are primarily valued using quoted inactive market prices, or quoted active market prices for similar securities, or by utilizing calculations which incorporate observable inputs such as yield, maturity and credit quality. These instruments are classified as Level 2. Mutual funds, partnerships, and common and collective trusts are valued utilizing a net asset value (NAV) concept or its equivalent. Mutual funds, which includes exchange traded funds (ETFs), are classified as Level 1 and valued using a NAV that is observable and based on the active market in which the fund trades. Common and collective trusts are maintained by banks or investment companies and hold certain investments in accordance with a stated set of objectives (such as tracking the performance of the S&P 500 Index). The trust's shares are offered to a limited group of investors, and are not traded in an active market. Investments in common and collective trusts are valued using NAV as a practical expedient and, accordingly, are not classified in the fair value hierarchy. The NAV for trusts investing in exchange traded equities, and fixed income securities is derived from the market prices of the underlying securities held by the trusts. The NAV for trusts investing in real estate is derived from the appraised values of the trust's underlying real estate assets. As of December 31, 2017, the plans were able to transact in the common and collective trusts at NAV. Investments in partnerships are also valued using the concept of NAV as a practical expedient and, accordingly, are not classified in the fair value hierarchy. The NAV for these investments is derived from the value of the partnerships' underlying assets. The plan's partnerships holdings relate to investments in high-yield fixed income instruments and assets of privately held portfolio companies. Certain partnerships also include funding commitments that may require the plan to contribute up to $75 million to these partnerships; as of December 31, 2017, approximately $58 million of these commitments have been funded. The plans’ trustee provides valuation of our plan assets by using pricing services that utilize methodologies described to determine fair market value. We have internal control procedures to ensure this information is consistent with fair value accounting guidance. These procedures include assessing valuations using an independent pricing source, verifying that pricing can be supported by actual recent market transactions, assessing hierarchy classifications, comparing investment returns with benchmarks, and obtaining and reviewing independent audit reports on the trustee’s internal operating controls and valuation processes. The fair value of Pinnacle West’s pension plan and other postretirement benefit plan assets at December 31, 2017, by asset category, are as follows (dollars in thousands):
| Quoted Prices in Active Markets for Identical Assets (Level 1) |  | Significant Other Observable Inputs (Level 2) |  | Other (a) |  | Balance at December 31, 2017
Pension Plan: |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | 3,830 |  |  | $ | — |  |  | $ | — |  |  | $ | 3,830 |
Fixed income securities: |  |  |  |  |  |  |  |  |  |
Corporate | — |  |  | 1,365,194 |  |  | — |  |  | 1,365,194 |
U.S. Treasury | 221,291 |  |  | — |  |  | — |  |  | 221,291 |
Other (b) | — |  |  | 100,599 |  |  | — |  |  | 100,599 |
Common stock equities (c) | 228,088 |  |  | — |  |  | — |  |  | 228,088 |
Mutual funds (d) | 233,732 |  |  | — |  |  | — |  |  | 233,732 |
Common and collective trusts: |  |  |  |  |  |  |
Equities | — |  |  | — |  |  | 408,763 |  |  | 408,763 |
Real estate | — |  |  | — |  |  | 171,569 |  |  | 171,569 |
Fixed Income | — |  |  | — |  |  | 90,869 |  |  | 90,869 |
Partnerships | — |  |  | — |  |  | 133,379 |  |  | 133,379 |
Short-term investments and other (e) | — |  |  | 1,208 |  |  | 98,505 |  |  | 99,713 |
Total | $ | 686,941 |  |  | $ | 1,467,001 |  |  | $ | 903,085 |  |  | $ | 3,057,027 |
Other Benefits: |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | 143 |  |  | $ | — |  |  | $ | — |  |  | $ | 143 |
Fixed income securities: |  |  |  |  |  |  |  |  |  |
Corporate | — |  |  | 306,008 |  |  | — |  |  | 306,008 |
U.S. Treasury | 336,963 |  |  | — |  |  | — |  |  | 336,963 |
Other (b) | — |  |  | 32,508 |  |  | — |  |  | 32,508 |
Common stock equities (c) | 196,153 |  |  | — |  |  | — |  |  | 196,153 |
Mutual funds (d) | 39,269 |  |  | — |  |  | — |  |  | 39,269 |
Common and collective trusts: |  |  |  |  |  |  |  |  |  |
Equities | — |  |  | — |  |  | 75,310 |  |  | 75,310 |
Real estate | — |  |  | — |  |  | 15,422 |  |  | 15,422 |
Short-term investments and other (e) | 11,268 |  |  | 149 |  |  | 9,178 |  |  | 20,595 |
Total | $ | 583,796 |  |  | $ | 338,665 |  |  | $ | 99,910 |  |  | $ | 1,022,371 |
(a) | These investments primarily represent assets valued using net asset value as a practical expedient, and have not been classified in the fair value hierarchy.
(b) | This category consists primarily of debt securities issued by municipalities.
(c) | This category primarily consists of U.S. common stock equities.
(d) | These funds invest in U.S. and international common stock equities.
(e) | This category includes plan receivables and payables.
The fair value of Pinnacle West’s pension plan and other postretirement benefit plan assets at December 31, 2016, by asset category, are as follows (dollars in thousands):
| Quoted Prices in Active Markets for Identical Assets (Level 1) |  | Significant Other Observable Inputs (Level 2) |  | Other (a) |  | Balance at December 31, 2016
Pension Plan: |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | 13,995 |  |  | $ | — |  |  | $ | — |  |  | $ | 13,995 |
Fixed income securities: |  |  |  |  |  |  |  |  |  |
Corporate | — |  |  | 1,210,453 |  |  | — |  |  | 1,210,453 |
U.S. Treasury | 112,583 |  |  | — |  |  | — |  |  | 112,583 |
Other (b) | — |  |  | 102,170 |  |  | — |  |  | 102,170 |
Common stock equities (c) | 235,109 |  |  | — |  |  | — |  |  | 235,109 |
Mutual funds (d) | 251,506 |  |  | — |  |  | — |  |  | 251,506 |
Common and collective trusts: |  |  |  |  |  |  |
Equities | — |  |  | — |  |  | 266,840 |  |  | 266,840 |
Real estate | — |  |  | — |  |  | 161,449 |  |  | 161,449 |
Partnerships | — |  |  | — |  |  | 208,915 |  |  | 208,915 |
Short-term investments and other (e) | — |  |  | — |  |  | 112,337 |  |  | 112,337 |
Total | $ | 613,193 |  |  | $ | 1,312,623 |  |  | $ | 749,541 |  |  | $ | 2,675,357 |
Other Benefits: |  |  |  |  |  |  |  |  |  |  |
Cash and cash equivalents | $ | 304 |  |  | $ | — |  |  | $ | — |  |  | $ | 304 |
Fixed income securities: |  |  |  |  |  |  |  |  |  |
Corporate | — |  |  | 268,193 |  |  | — |  |  | 268,193 |
U.S. Treasury | 145,255 |  |  | — |  |  | — |  |  | 145,255 |
Other (b) | — |  |  | 34,506 |  |  | — |  |  | 34,506 |
Common stock equities (c) | 243,741 |  |  | — |  |  | — |  |  | 243,741 |
Mutual funds (d) | 67,418 |  |  | — |  |  | — |  |  | 67,418 |
Common and collective trusts: |  |  |  |  |  |  |
Equities | — |  |  | — |  |  | 95,814 |  |  | 95,814 |
Real estate | — |  |  | — |  |  | 14,509 |  |  | 14,509 |
Partnerships | — |  |  | — |  |  | 3,060 |  |  | 3,060 |
Short-term investments and other (e) | — |  |  | — |  |  | 9,851 |  |  | 9,851 |
Total | $ | 456,718 |  |  | $ | 302,699 |  |  | $ | 123,234 |  |  | $ | 882,651 |
(a) | These investments primarily represent assets valued using net asset value as a practical expedient, and have not been classified in the fair value hierarchy.
(b) | This category consists primarily of debt securities issued by municipalities.
(c) | This category primarily consists of U.S. common stock equities.
(d) | These funds invest in U.S. and international common stock equities.
(e) | This category includes plan receivables and payables.
Contributions Future year contribution amounts are dependent on plan asset performance and plan actuarial assumptions. We made contributions to our pension plan totaling $100 million in 2017, $100 million in 2016, and $100 million in 2015. 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 $250 million during the 2018-2020 period. With regard to contributions to our other postretirement benefit plans, we made a contribution of approximately $1 million in each of 2017, 2016 and 2015. We do not expect to make any contributions over the next three years to our other postretirement benefit plans. APS funds its share of the contributions. APS’s share of the pension plan contribution was approximately $100 million in 2017, $100 million in 2016 and $100 million in 2015. APS’s share of the contributions to the other postretirement benefit plan was approximately $1 million in 2017, 2016 and 2015. Estimated Future Benefit Payments Benefit payments, which reflect estimated future employee service, for the next five years and the succeeding five years thereafter, are estimated to be as follows (dollars in thousands):
Year |  | Pension |  | Other Benefits
2018 |  | $ | 175,383 |  |  | $ | 31,891 |
2019 |  | 181,902 |  |  | 34,000 |
2020 |  | 191,586 |  |  | 35,658 |
2021 |  | 196,583 |  |  | 37,090 |
2022 |  | 201,463 |  |  | 37,860 |
Years 2023-2027 |  | 1,068,568 |  |  | 191,207 |
Electric plant participants contribute to the above amounts in accordance with their respective participation agreements. Employee Savings Plan Benefits Pinnacle West sponsors a defined contribution savings plan for eligible employees of Pinnacle West and its subsidiaries. In 2017, costs related to APS’s employees represented 99% of the total cost of this plan. In a defined contribution savings plan, the benefits a participant receives result from regular contributions participants make to their own individual account, the Company’s matching contributions and earnings or losses on their investments. Under this plan, the Company matches a percentage of the participants’ contributions in cash which is then invested in the same investment mix as participants elect to invest their own future contributions. Pinnacle West recorded expenses for this plan of approximately $10 million for 2017, $10 million for 2016, and $9 million for 2015.

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