We maintain contributory and non-contributory retirement plans for eligible employees. Our contributions to the contributory plan amounted to $56.6 million, $50.1 million and $45.7 million in 2018, 2017 and 2016, respectively. The non-contributory plan is a defined benefit pension plan which covers employees of one of our subsidiaries. The benefits are based on years of service and the employee’s highest compensation for any five years of employment. Our funding policy is to contribute annually at least the minimum amount that should be funded in accordance with the provisions of ERISA.

For defined benefit pension plans, the benefit obligation is the “projected benefit obligation”, the actuarial present value, as of December 31 measurement date, of all benefits attributed by the pension benefit formula to employee service rendered to that date. The amount of benefit to be paid depends on a number of future events incorporated into the pension benefit formula, including estimates of the average life of employees/survivors and average years of service rendered. It is measured based on assumptions concerning future interest rates and future compensation levels. The following table shows the reconciliation of the defined benefit pension plan as of December 31, 2018 and 2017:

	2018			2017
	(000s)
Change in plan assets:
Fair value of plan assets at beginning of year	$	118,667		$	109,677
Actual return (loss) on plan assets		(7,522	)		15,533
Benefits paid		(6,031	)		(5,846	)
Administrative expenses		(523	)		(697	)
Fair value of plan assets at end of year	$	104,591		$	118,667
Change in benefit obligation:
Benefit obligation at beginning of year	$	116,056		$	110,949
Service cost		689			721
Interest cost		4,063			4,465
Benefits paid		(6,031	)		(5,846	)
Actuarial (gain) loss		(6,350	)		5,767
Benefit obligation at end of year	$	108,427		$	116,056
Amounts recognized in the Consolidated Balance Sheet:
Other non-current assets					2,611
Other non-current liabilities		3,836
Total amounts recognized at end of year	$	3,836		$	2,611

	2018			2017			2016
	(000s)
Components of net periodic cost (benefit)
Service cost	$	689		$	721		$	926
Interest cost		4,063			4,465			4,997
Expected return on plan assets		(5,197	)		(5,862	)		(5,708	)
Amortization of actuarial loss		—			863			3,072
Net periodic cost	$	(445	)	$	187		$	3,287

	2018			2017
Weighted average assumptions as of December 31
Discount rate		4.03	%		3.60	%
Rate of compensation increase		4.00	%		4.00	%

	2018			2017			2016
Weighted-average assumptions for net periodic benefit cost calculations
Discount rate		3.60	%		4.14	%		4.34	%
Expected long-term rate of return on plan assets		4.50	%		5.50	%		5.50	%
Rate of compensation increase		4.00	%		4.00	%		4.00	%

The accumulated benefit obligation for our pension plan represents the actuarial present value of benefits based on employee service and compensation as of a certain date and does not include an assumption about future compensation levels. The accumulated benefit obligation for our plan was $108.3 million and $115.9 million as of December 31, 2018 and 2017, respectively. As of December 31, 2018, the accumulated benefit obligation exceeded the fair value of plan assets by $3.7 million. As of December 31, 2017, the fair value of plan assets exceeded the accumulated benefit obligation by $2.7 million.

We estimate that there will be no net loss or prior service cost amortized from accumulated other comprehensive income during 2019.

In May, 2015, the FASB issued ASU No. 2015-07, "Disclosures for Investments in Certain Entities That Calculate Net Asset Value per Share (or its Equivalent)," which is effective for annual reporting periods beginning after December 15, 2015. The standard removes the requirement to categorize investments for which fair value is measured using the net asset value (NAV) per share practical expedient within the fair value hierarchy. We have adopted this standard effective January 1, 2016, and applied the guidance retrospectively. This standard impacts financial statement disclosure only. In previous reporting periods, we disclosed the full fair value hierarchy and disclosed our pension assets as level 2 within the hierarchy. Going forward, we will disclose our pension assets by asset category reported using NAV as a practical expedient for comparative years.

The market values of our pension plan assets at December 31, 2018 and December 31, 2017, reported using net asset value as a practical expedient, by asset category are as follows:

	2018		2017
Equities:
U.S. Large Cap	$	7,711	$	9,393
U.S. Mid Cap		2,309		2,937
U.S. Small Cap		2,094		3,005
International Developed		5,710		7,213
Emerging Markets		4,137		4,792
Fixed income:
Core Fixed Income		24,617		25,915
Long Duration Fixed Income		55,318		62,522
Real Estate:
REIT Fund		2,037		2,370
Cash/Currency:
Cash Equivalents		658		520
Total market value	$	104,591	$	118,667

To develop the expected long-term rate of return on plan assets assumption, we considered the historical returns and the future expectations for returns for each asset class, as well as the target asset allocation of the pension portfolio.

The following table shows expected benefit payments for the years ended December 31, 2019 through 2028 for our defined pension plan. There will be benefit payments under this plan beyond 2028.

Estimated Future Benefit Payments (000s)
2019	$	6,595
2020		6,744
2021		6,834
2022		6,891
2023		6,921
2024-2028		34,270
Total	$	68,255

	2018			2017
Plan Assets
Asset Category
Equity securities		21	%		23	%
Fixed income securities		76	%		75	%
Other		3	%		2	%
Total		100	%		100	%

Investment Policy, Guidelines and Objectives have been established for the defined benefit pension plan. The investment policy is in keeping with the fiduciary requirements under existing federal laws and managed in accordance with the Prudent Investor Rule. Total portfolio risk is regularly evaluated and compared to that of the plan’s policy target allocation and judged on a relative basis over a market cycle. The following asset allocation policy and ranges have been established in accordance with the overall risk and return objectives of the portfolio:

In accordance with the investment policy, the portfolio will invest in high quality, large and small capitalization companies traded on national exchanges, and investment grade securities. The investment managers will not write or buy options for speculative purposes; securities may not be margined or sold short. The manager may employ futures or options for the purpose of hedging exposure, and will not purchase unregistered sectors, private placements, partnerships or commodities.