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Benefit Plans and Other Postretirement Benefits
12 Months Ended
Dec. 31, 2016
Compensation and Retirement Disclosure [Abstract]  
Benefit Plans and Other Postretirement Benefits
Benefit Plans and Other Postretirement Benefits

Consistent with the process for rate recovery of pension and postretirement benefits for its employees, PSCo accounts for its participation in, and related costs of, pension and other postretirement benefit plans sponsored by Xcel Energy Inc. as multiple employer plans. PSCo is responsible for its share of cash contributions, plan costs and obligations and is entitled to its share of plan assets; accordingly, PSCo accounts for its pro rata share of these plans, including pension expense and contributions, resulting in accounting consistent with that of a single employer plan exclusively for PSCo employees.

Xcel Energy, which includes PSCo, offers various benefit plans to its employees. Approximately 77 percent of employees that receive benefits are represented by several local labor unions under several collective-bargaining agreements. At Dec. 31, 2016, PSCo had 1,984 bargaining employees covered under a collective-bargaining agreement, which expires in May 2017.

The plans invest in various instruments which are disclosed under the accounting guidance for fair value measurements which establishes a hierarchical framework for disclosing the observability of the inputs utilized in measuring fair value. The three levels in the hierarchy and examples of each level are as follows:

Level 1 — Quoted prices are available in active markets for identical assets as of the reporting date. The types of assets included in Level 1 are highly liquid and actively traded instruments with quoted prices.

Level 2 — Pricing inputs are other than quoted prices in active markets, but are either directly or indirectly observable as of the reporting date. The types of assets included in Level 2 are typically either comparable to actively traded securities or contracts, or priced with models using highly observable inputs.

Level 3 — Significant inputs to pricing have little or no observability as of the reporting date. The types of assets included in Level 3 are those with inputs requiring significant management judgment or estimation.

Specific valuation methods include the following:

Cash equivalents The fair values of cash equivalents are generally based on cost plus accrued interest; money market funds are measured using quoted NAVs.

Insurance contracts — Insurance contract fair values take into consideration the value of the investments in separate accounts of the insurer, which are priced based on observable inputs.

Investments in commingled funds, equity securities and other funds — Equity securities are valued using quoted prices in active markets. The fair values for commingled funds are measured using NAVs, which take into consideration the value of underlying fund investments, as well as the other accrued assets and liabilities of a fund, in order to determine a per share market value. The investments in commingled funds may be redeemed for NAV with proper notice. Proper notice varies by fund and can range from daily with a few days’ notice to annually with 90 days’ notice. Private equity investments require approval of the fund for any unscheduled redemption, and such redemptions may be approved or denied by the fund at its sole discretion. Depending on the fund, unscheduled distributions from real estate investments may require approval of the fund or may be redeemed with proper notice, which is typically quarterly with 45-90 days’ notice; however, withdrawals from real estate investments may be delayed or discounted as a result of fund illiquidity.

Investments in debt securities — Fair values for debt securities are determined by a third party pricing service using recent trades and observable spreads from benchmark interest rates for similar securities.

Derivative Instruments Fair values for foreign currency derivatives are determined using pricing models based on the prevailing forward exchange rate of the underlying currencies. The fair values of interest rate derivatives are based on broker quotes that utilize current market interest rate forecasts.

Pension Benefits

Xcel Energy, which includes PSCo, has several noncontributory, defined benefit pension plans that cover almost all employees. Generally, benefits are based on a combination of years of service, the employee’s average pay and, in some cases, social security benefits. Xcel Energy Inc.’s and PSCo’s policy is to fully fund into an external trust the actuarially determined pension costs recognized for ratemaking and financial reporting purposes, subject to the limitations of applicable employee benefit and tax laws.

In addition to the qualified pension plans, Xcel Energy maintains a supplemental executive retirement plan (SERP) and a nonqualified pension plan. The SERP is maintained for certain executives that were participants in the plan in 2008, when the SERP was closed to new participants. The nonqualified pension plan provides unfunded, nonqualified benefits for compensation that is in excess of the limits applicable to the qualified pension plans, with distributions attributable to PSCo funded by PSCo’s consolidated operating cash flows. The total obligations of the SERP and nonqualified plan as of Dec. 31, 2016 and 2015 were $43.5 million and $41.8 million, respectively, of which $3.8 million and $3.6 million were attributable to PSCo. In 2016 and 2015, Xcel Energy recognized net benefit cost for financial reporting for the SERP and nonqualified plans of $7.9 million and $9.5 million, respectively, of which $0.6 million in each year was attributable to PSCo.

In 2016, Xcel Energy established rabbi trusts to provide partial funding for future distributions of the SERP and its deferred compensation plan. Rabbi trust funding of deferred compensation plan distributions attributable to PSCo will be supplemented by PSCo’s consolidated operating cash flows as determined necessary. The amount of rabbi trust funding attributable to PSCo is immaterial. Also in 2016, Xcel Energy amended the deferred compensation plan to provide eligible participants the ability to diversify deferred settlements of equity awards, other than time-based equity awards, into various fund options.

Xcel Energy Inc. and PSCo base the investment-return assumption on expected long-term performance for each of the investment types included in the pension asset portfolio and consider the historical returns achieved by the asset portfolio over the past 20-year or longer period, as well as the long-term return levels projected and recommended by investment experts. Xcel Energy Inc. and PSCo continually review pension assumptions. The pension cost determination assumes a forecasted mix of investment types over the long term.

Investment returns in 2016 were below the assumed level of 6.84 percent;
Investment returns in 2015 were below the assumed level of 6.81 percent;
Investment returns in 2014 were above the assumed level of 6.81 percent; and
In 2017, PSCo’s expected investment-return assumption is 6.62 percent.

The assets are invested in a portfolio according to Xcel Energy Inc.’s and PSCo’s return, liquidity and diversification objectives to provide a source of funding for plan obligations and minimize the necessity of contributions to the plan, within appropriate levels of risk. The principal mechanism for achieving these objectives is the projected allocation of assets to selected asset classes, given the long-term risk, return, and liquidity characteristics of each particular asset class. There were no significant concentrations of risk in any particular industry, index, or entity. Market volatility can impact even well-diversified portfolios and significantly affect the return levels achieved by pension assets in any year.

The following table presents the target pension asset allocations for PSCo at Dec. 31 for the upcoming year:
 
 
2016
 
2015
Domestic and international equity securities
 
36
%
 
36
%
Long-duration fixed income and interest rate swap securities
 
31

 
32

Short-to-intermediate fixed income securities
 
15

 
12

Alternative investments
 
16

 
18

Cash
 
2

 
2

Total
 
100
%
 
100
%


The ongoing investment strategy is based on plan-specific investment recommendations that seek to minimize potential investment and interest rate risk as a plan’s funded status increases over time. The investment recommendations result in a greater percentage of long-duration fixed income securities being allocated to specific plans having relatively higher funded status ratios and a greater percentage of growth assets being allocated to plans having relatively lower funded status ratios. The aggregate projected asset allocation presented in the table above for the master pension trust results from the plan-specific strategies.

Pension Plan Assets

The following tables present, for each of the fair value hierarchy levels, PSCo’s pension plan assets that are measured at fair value as of Dec. 31, 2016 and 2015:
 
 
Dec. 31, 2016
(Thousands of Dollars)
 
Level 1
 
Level 2
 
Level 3
 
Investments Measured at NAV (a)
 
Total
Cash equivalents
 
$
34,957

 
$

 
$

 
$

 
$
34,957

Commingled funds:
 
 
 
 
 
 
 
 
 
 
U.S. equity funds
 

 

 

 
165,621

 
165,621

Non U.S. equity funds
 

 

 

 
122,197

 
122,197

U.S. corporate bond funds
 

 

 

 
96,995

 
96,995

Emerging market equity funds
 

 

 

 
64,784

 
64,784

Emerging market debt funds
 

 

 

 
53,703

 
53,703

Commodity funds
 

 

 

 
7,497

 
7,497

Private equity investments
 

 

 

 
31,828

 
31,828

Real estate
 

 

 

 
61,048

 
61,048

Other commingled funds
 

 

 

 
74,696

 
74,696

Debt securities:
 
 
 
 
 
 
 
 
 
 
Government securities
 

 
168,014

 

 

 
168,014

U.S. corporate bonds
 

 
86,081

 

 

 
86,081

Non U.S. corporate bonds
 

 
13,828

 

 

 
13,828

Mortgage-backed securities
 

 
2,179

 

 

 
2,179

Asset-backed securities
 

 
1,032

 

 

 
1,032

Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. equities
 
27,348

 

 

 

 
27,348

Other
 

 
(7,595
)
 

 

 
(7,595
)
Total
 
$
62,305

 
$
263,539

 
$

 
$
678,369

 
$
1,004,213

 
(a) 
Based on the requirements of ASU No. 2015-07, investments measured at fair value using a NAV methodology have not been classified in the fair value hierarchy. See Note 2 for further information on the adoption of ASU No. 2015-07.

 
 
Dec. 31, 2015
(Thousands of Dollars)
 
Level 1
 
Level 2
 
Level 3
 
Investments Measured at NAV (a)
 
Total
Cash equivalents
 
$
81,954

 
$

 
$

 
$

 
$
81,954

Derivatives
 

 
1,204

 

 

 
1,204

Commingled funds:
 
 
 
 
 
 
 
 
 
 
U.S. equity funds
 

 

 

 
125,011

 
125,011

Non U.S. equity funds
 

 

 

 
119,394

 
119,394

U.S. corporate bond funds
 

 

 

 
82,827

 
82,827

Emerging market equity funds
 

 

 

 
56,525

 
56,525

Emerging market debt funds
 

 

 

 
54,362

 
54,362

Commodity funds
 

 

 

 
14,169

 
14,169

Private equity investments
 

 

 

 
34,353

 
34,353

Real estate
 

 

 

 
67,075

 
67,075

Other commingled funds
 

 

 

 
72,327

 
72,327

Debt securities:
 
 
 
 
 
 
 
 
 
 
Government securities
 

 
214,341

 

 

 
214,341

U.S. corporate bonds
 

 
74,787

 

 

 
74,787

Non U.S. corporate bonds
 

 
12,127

 

 

 
12,127

Asset-backed securities
 

 
881

 

 

 
881

Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. equities
 
28,797

 

 

 

 
28,797

Other
 

 
(3,453
)
 

 

 
(3,453
)
Total
 
$
110,751

 
$
299,887

 
$

 
$
626,043

 
$
1,036,681



(a) 
Based on the requirements of ASU No. 2015-07, investments measured at fair value using a NAV methodology have not been classified in the fair value hierarchy. See Note 2 for further information on the adoption of ASU No. 2015-07.

There were no assets transferred in or out of Level 3 for the years ended Dec. 31, 2016, 2015 or 2014.

Benefit Obligations — A comparison of the actuarially computed pension benefit obligation and plan assets for PSCo is presented in the following table:
(Thousands of Dollars)
 
2016
 
2015
Accumulated Benefit Obligation at Dec. 31
 
$
1,213,890

 
$
1,192,798

 
 
 
 
 
Change in Projected Benefit Obligation:
 
 
 
 
Obligation at Jan. 1
 
$
1,224,650

 
$
1,277,957

Service cost
 
25,926

 
28,260

Interest cost
 
55,405

 
50,857

Transfer to other plan
 
(9,149
)
 
(2,938
)
Plan amendments
 
206

 

Actuarial loss (gain)
 
51,779

 
(54,737
)
Benefit payments
 
(96,995
)
 
(74,749
)
Obligation at Dec. 31
 
$
1,251,822

 
$
1,224,650


(Thousands of Dollars)
 
2016
 
2015
Change in Fair Value of Plan Assets:
 
 
 
 
Fair value of plan assets at Jan. 1
 
$
1,036,681

 
$
1,103,865

Actual return (loss) on plan assets
 
56,762

 
(9,122
)
Employer contributions
 
16,829

 
20,056

Transfer to other plan
 
(9,064
)
 
(3,369
)
Benefit payments
 
(96,995
)
 
(74,749
)
Fair value of plan assets at Dec. 31
 
$
1,004,213

 
$
1,036,681



(Thousands of Dollars)
 
2016
 
2015
Funded Status of Plans at Dec. 31:
 
 
 
 
Funded status (a)
 
$
(247,609
)
 
$
(187,969
)

(a) 
Amounts are recognized in noncurrent liabilities on PSCo’s consolidated balance sheets.
(Thousands of Dollars)
 
2016
 
2015
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost:
 
 
 
 
Net loss
 
$
554,999

 
$
521,703

Prior service credit
 
(12,155
)
 
(15,572
)
Total
 
$
542,844

 
$
506,131


(Thousands of Dollars)
 
2016
 
2015
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates:
 
 
 
 
Current regulatory assets
 
$
515,708

 
$
28,852

Noncurrent regulatory assets
 
26,853

 
477,279

Deferred income taxes
 
108

 

Net-of-tax accumulated OCI
 
175

 

Total
 
$
542,844

 
$
506,131


Measurement date
 
Dec. 31, 2016
 
Dec. 31, 2015
 
 
2016
 
2015
Significant Assumptions Used to Measure Benefit Obligations:
 
 
 
 
Discount rate for year-end valuation
 
4.13
%
 
4.66
%
Expected average long-term increase in compensation level
 
3.75

 
4.00

Mortality table
 
RP-2014

 
RP-2014



Mortality — In 2014, the Society of Actuaries published a new mortality table (RP-2014) and projection scale (MP-2014) that increased the overall life expectancy of males and females. On Dec. 31, 2014 PSCo adopted the RP-2014 table, with modifications, based on its population and specific experience and a modified MP-2014 projection scale. During 2016, a new projection table was released (MP-2016).  In 2016, PSCo adopted a modified version of the MP-2016 table and will continue to utilize the RP-2014 base table, modified for company experience.

Cash Flows — Cash funding requirements can be impacted by changes to actuarial assumptions, actual asset levels and other calculations prescribed by the funding requirements of income tax and other pension-related regulations. Required contributions were made in 2014 through 2017 to meet minimum funding requirements.

Total voluntary and required pension funding contributions across all four of Xcel Energy’s pension plans were as follows:

$150.0 million in January 2017, of which $16.8 million was attributable to PSCo;
$125.2 million in 2016, of which $16.8 million was attributable to PSCo;
$90.1 million in 2015, of which $20.1 million was attributable to PSCo; and
$130.6 million in 2014, of which $35.2 million was attributable to PSCo.

For future years, Xcel Energy and PSCo anticipate contributions will be made as necessary.

Plan Amendments — The 2016 increase in the projected benefit obligation resulted from an increase in the annual credits contributed to the PSCo Bargaining Plan retirement spending account. In 2015, there were no plan amendments made which affected the projected benefit obligation.

Benefit Costs The components of PSCo’s net periodic pension cost were:
(Thousands of Dollars)
 
2016
 
2015
 
2014
Service cost
 
$
25,926

 
$
28,260

 
$
23,939

Interest cost
 
55,405

 
50,857

 
53,277

Expected return on plan assets
 
(70,769
)
 
(72,590
)
 
(70,709
)
Amortization of prior service credit
 
(3,211
)
 
(3,136
)
 
(3,092
)
Amortization of net loss
 
26,771

 
36,377

 
33,892

Net periodic pension cost
 
34,122

 
39,768

 
37,307

Credits (costs) not recognized due to effects of regulation
 
3,364

 
(1,464
)
 

Net benefit cost recognized for financial reporting
 
$
37,486

 
$
38,304

 
$
37,307



 
 
2016
 
2015
 
2014
Significant Assumptions Used to Measure Costs:
 
 
 
 
 
 
Discount rate
 
4.66
%
 
4.11
%
 
4.75
%
Expected average long-term increase in compensation level
 
4.00

 
3.75

 
3.75

Expected average long-term rate of return on assets
 
6.84

 
6.81

 
6.81


 
In addition to the benefit costs in the table above, for the pension plans sponsored by Xcel Energy Inc., costs are allocated to PSCo based on Xcel Energy Services Inc. employees’ labor costs. Amounts allocated to PSCo were $9.4 million, $9.9 million and $9.4 million in 2016, 2015 and 2014, respectively. Pension costs include an expected return impact for the current year that may differ from actual investment performance in the plan. The return assumption used for 2017 pension cost calculations is 6.62 percent. The cost calculation uses a market-related valuation of pension assets. Xcel Energy, including PSCo, uses a calculated value method to determine the market-related value of the plan assets. The market-related value begins with the fair market value of assets as of the beginning of the year. The market-related value is determined by adjusting the fair market value of assets to reflect the investment gains and losses (the difference between the actual investment return and the expected investment return on the market-related value) during each of the previous five years at the rate of 20 percent per year. As these differences between actual investment returns and the expected investment returns are incorporated into the market-related value, the differences are recognized over the expected average remaining years of service for active employees.

Defined Contribution Plans

Xcel Energy, which includes PSCo, maintains 401(k) and other defined contribution plans that cover substantially all employees. The expense to these plans for PSCo was approximately $9.9 million in 2016, $9.5 million in 2015 and $9.1 million in 2014.

Postretirement Health Care Benefits

Xcel Energy, which includes PSCo, has a contributory health and welfare benefit plan that provides health care and death benefits to certain retirees. Xcel Energy discontinued contributing toward health care benefits for PSCo nonbargaining employees retiring after June 30, 2003. Employees of NCE who retired in 2002 continue to receive employer-subsidized health care benefits. Nonbargaining employees of the former NCE who retired after 1998, bargaining employees of the former NCE who retired after 1999 and nonbargaining employees of NCE who retired after June 30, 2003, are eligible to participate in the Xcel Energy health care program with no employer subsidy.

Plan Assets — Certain state agencies that regulate Xcel Energy Inc.’s utility subsidiaries also have issued guidelines related to the funding of postretirement benefit costs. PSCo is required to fund postretirement benefit costs in irrevocable external trusts that are dedicated to the payment of these postretirement benefits. These assets are invested in a manner consistent with the investment strategy for the pension plan.

The following table presents the target postretirement asset allocations for Xcel Energy Inc. and PSCo at Dec. 31 for the upcoming year:
 
 
2016
 
2015
Domestic and international equity securities
 
25
%
 
25
%
Short-to-intermediate fixed income securities
 
57

 
57

Alternative investments
 
13

 
13

Cash
 
5

 
5

Total
 
100
%
 
100
%


Xcel Energy Inc. and PSCo base the investment-return assumptions for the postretirement health care fund assets on expected long-term performance for each of the investment types included in the asset portfolio. Assumptions and target allocations are determined at the master trust level. The investment mix at each of Xcel Energy Inc.’s utility subsidiaries may vary from the investment mix of the total asset portfolio. The assets are invested in a portfolio according to Xcel Energy Inc.’s and PSCo’s return, liquidity and diversification objectives to provide a source of funding for plan obligations and minimize the necessity of contributions to the plan, within appropriate levels of risk. The principal mechanism for achieving these objectives is the projected allocation of assets to selected asset classes, given the long-term risk, return, correlation and liquidity characteristics of each particular asset class. There were no significant concentrations of risk in any particular industry, index, or entity. Market volatility can impact even well-diversified portfolios and significantly affect the return levels achieved by postretirement health care assets in any year.

The following tables present, for each of the fair value hierarchy levels, PSCo’s proportionate allocation of the total postretirement benefit plan assets that are measured at fair value as of Dec. 31, 2016 and 2015:
 
 
Dec. 31, 2016
(Thousands of Dollars)
 
Level 1
 
Level 2
 
Level 3
 
Investments Measured at NAV (a)
 
Total
Cash equivalents
 
$
18,288

 
$

 
$

 
$

 
$
18,288

Insurance contracts
 

 
42,046

 

 

 
42,046

Commingled funds:
 
 
 
 
 
 
 
 
 
 
U.S. equity funds
 

 

 

 
48,462

 
48,462

U.S fixed income funds
 

 

 

 
24,132

 
24,132

Emerging market debt funds
 

 

 

 
27,089

 
27,089

Other commingled funds
 

 

 

 
48,922

 
48,922

Debt securities:
 
 
 
 
 
 
 
 
 
 
Government securities
 

 
33,600

 

 

 
33,600

U.S. corporate bonds
 

 
55,473

 

 

 
55,473

Non U.S. corporate bonds
 

 
15,384

 

 

 
15,384

Asset-backed securities
 

 
16,845

 

 

 
16,845

Mortgage-backed securities
 

 
25,563

 

 

 
25,563

Equity securities:
 
 
 
 
 
 
 
 
 
 
Non U.S. equities
 
36,462

 

 

 

 
36,462

Other
 

 
1,289

 

 

 
1,289

Total
 
$
54,750

 
$
190,200

 
$

 
$
148,605

 
$
393,555

(a) 
Based on the requirements of ASU No. 2015-07, investments measured at fair value using a NAV methodology have not been classified in the fair value hierarchy. See Note 2 for further information on the adoption of ASU No. 2015-07.

 
 
Dec. 31, 2015
(Thousands of Dollars)
 
Level 1
 
Level 2
 
Level 3
 
Investments Measured at NAV (a)

 
Total
Cash equivalents
 
$
17,524

 
$

 
$

 
$

 
$
17,524

Insurance contracts
 

 
42,123

 

 

 
42,123

Commingled funds:
 
 
 
 
 
 
 
 
 
 
U.S. equity funds
 

 

 

 
34,089

 
34,089

Non U.S. equity funds
 

 

 

 
29,979

 
29,979

U.S fixed income funds
 

 

 

 
21,638

 
21,638

Emerging market equity funds
 

 

 

 
9,901

 
9,901

Emerging market debt funds
 

 

 

 
31,827

 
31,827

Other commingled funds
 

 

 

 
55,302

 
55,302

Debt securities:
 
 
 
 
 
 
 
 
 
 
Government securities
 

 
35,016

 

 

 
35,016

U.S. corporate bonds
 

 
53,433

 

 

 
53,433

Non U.S. corporate bonds
 

 
11,598

 

 

 
11,598

Asset-backed securities
 

 
25,602

 

 

 
25,602

Mortgage-backed securities
 

 
31,778

 

 

 
31,778

Other
 

 
(368
)
 

 

 
(368
)
Total
 
$
17,524

 
$
199,182

 
$

 
$
182,736

 
$
399,442


(a) 
Based on the requirements of ASU No. 2015-07, investments measured at fair value using a NAV methodology have not been classified in the fair value hierarchy. See Note 2 for further information on the adoption of ASU No. 2015-07.

There were no assets transferred in or out of Level 3 for the years ended Dec. 31, 2016, 2015 or 2014.

Benefit Obligations — A comparison of the actuarially computed benefit obligation and plan assets for PSCo is presented in the following table:
(Thousands of Dollars)
 
2016
 
2015
Change in Projected Benefit Obligation:
 
 
 
 
Obligation at Jan. 1
 
$
403,574

 
$
443,753

Service cost
 
768

 
928

Interest cost
 
18,070

 
17,498

Medicare subsidy reimbursements
 
1,901

 
1,712

Plan participants’ contributions
 
5,376

 
4,961

Actuarial loss (gain)
 
27,355

 
(32,001
)
Benefit payments
 
(35,221
)
 
(33,277
)
Obligation at Dec. 31
 
$
421,823

 
$
403,574


(Thousands of Dollars)
 
2016
 
2015
Change in Fair Value of Plan Assets:
 
 
 
 
Fair value of plan assets at Jan. 1
 
$
399,442

 
$
425,282

Actual return (loss) on plan assets
 
18,590

 
(3,076
)
Plan participants’ contributions
 
5,376

 
4,961

Employer contributions
 
5,368

 
5,552

Benefit payments
 
(35,221
)
 
(33,277
)
Fair value of plan assets at Dec. 31
 
$
393,555

 
$
399,442


(Thousands of Dollars)
 
2016
 
2015
Funded Status at Dec. 31:
 
 
 
 
Funded status (a)
 
$
(28,268
)
 
$
(4,132
)

(a) 
Amounts are recognized in noncurrent liabilities on PSCo’s consolidated balance sheets.
(Thousands of Dollars)
 
2016
 
2015
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost:
 
 
 
 
Net loss
 
$
78,359

 
$
49,226

Prior service credit
 
(27,695
)
 
(33,942
)
Total
 
$
50,664

 
$
15,284


(Thousands of Dollars)
 
2016
 
2015
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates:
 
 
 
 
Noncurrent regulatory assets
 
$
50,664

 
$
15,284


Measurement date
 
Dec. 31, 2016
 
Dec. 31, 2015
 
 
2016
 
2015
Significant Assumptions Used to Measure Benefit Obligations:
 
 
 
 
Discount rate for year-end valuation
 
4.13
%
 
4.65
%
Mortality table
 
RP 2014

 
RP 2014

Health care costs trend rate — initial
 
5.50
%
 
6.00
%


Effective Jan. 1, 2017, the initial medical trend rate was decreased from 6.0 percent to 5.5 percent. The ultimate trend assumption remained at 4.5 percent. The period until the ultimate rate is reached is two years. Xcel Energy Inc. and PSCo base the medical trend assumption on the long-term cost inflation expected in the health care market, considering the levels projected and recommended by industry experts, as well as recent actual medical cost increases experienced by the retiree medical plan.

A one-percent change in the assumed health care cost trend rate would have the following effects on PSCo:
 
 
One-Percentage Point
(Thousands of Dollars)
 
Increase
 
Decrease
APBO
 
$
40,100

 
$
(34,155
)
Service and interest components
 
1,980

 
(1,677
)


Cash Flows — The postretirement health care plans have no funding requirements under income tax and other retirement-related regulations other than fulfilling benefit payment obligations, when claims are presented and approved under the plans. Additional cash funding requirements are prescribed by certain state and federal rate regulatory authorities. Xcel Energy, which includes PSCo, contributed $17.9 million, $18.3 million and $17.1 million during 2016, 2015 and 2014, respectively, of which $5.4 million, $5.6 million and $5.5 million were attributable to PSCo. Xcel Energy expects to contribute approximately $11.8 million during 2017, of which amounts attributable to PSCo will be zero.

Plan Amendments — In 2016 and 2015 there were no plan amendments made which affected the projected benefit obligation.

Benefit Costs — The components of PSCo’s net periodic postretirement benefit costs were:
(Thousands of Dollars)
 
2016
 
2015
 
2014
Service cost
 
$
768

 
$
928

 
$
1,915

Interest cost
 
18,070

 
17,498

 
23,704

Expected return on plan assets
 
(22,299
)
 
(23,803
)
 
(30,214
)
Amortization of prior service credit
 
(6,247
)
 
(6,247
)
 
(6,247
)
Amortization of net loss
 
1,931

 
2,475

 
6,434

Net periodic postretirement benefit credit
 
$
(7,777
)
 
$
(9,149
)
 
$
(4,408
)

 
 
2016
 
2015
 
2014
Significant Assumptions Used to Measure Costs:
 
 
 
 
 
 
Discount rate
 
4.65
%
 
4.08
%
 
4.82
%
Expected average long-term rate of return on assets
 
5.80

 
5.80

 
7.18



In addition to the benefit costs in the table above, for the postretirement health care plans sponsored by Xcel Energy Inc., costs are allocated to PSCo based on Xcel Energy Services Inc. employees’ labor costs.

Projected Benefit Payments

The following table lists PSCo’s projected benefit payments for the pension and postretirement benefit plans:
(Thousands of Dollars)
 
Projected Pension
Benefit Payments
 
Gross Projected
Postretirement
Health Care
Benefit Payments
 
Expected Medicare
Part D Subsidies
 
Net Projected
Postretirement
Health Care
Benefit Payments
2017
 
$
79,506

 
$
33,912

 
$
2,140

 
$
31,772

2018
 
78,738

 
33,652

 
2,266

 
31,386

2019
 
80,914

 
33,467

 
2,383

 
31,084

2020
 
81,095

 
33,991

 
2,475

 
31,516

2021
 
82,084

 
33,588

 
2,574

 
31,014

2022-2026
 
417,876

 
156,773

 
14,246

 
142,527