We sponsor a defined contribution plan in which we match our employees’ qualifying contributions, resulting in additional expense to us. Expenses related to the defined contribution plan were $4.1 million and $4.5 million for the three months ended March 31, 2019 and 2020, respectively.

In addition, we sponsor two pension plans, including one for all non-union employees and one that covers certain union employees, and a postretirement benefit plan for certain employees. Prior to the March 2020 sale of our New Haven terminal (See Note 1 – Organization, Description of Business and Basis of Presentation), we sponsored an additional union pension plan that covered union employees at that terminal. Net periodic benefit expense for the three months ended March 31, 2019 and 2020 was as follows (in thousands):



	Three Months Ended					Three Months Ended
	March 31, 2019					March 31, 2020
	Pension Benefits			Other Postretirement Benefits		Pension Benefits			Other Postretirement Benefits
Components of net periodic benefit costs:
Service cost	$	6,527		$	54	$	7,203		$	62
Interest cost	3,000			119		2,802			112
Expected return on plan assets	(2,374		)	—		(2,886		)	—
Amortization of prior service credit	(45		)	—		(45		)	—
Amortization of actuarial loss	1,277			71		1,412			119
Settlement cost	—			—		969			—
Settlement gain on disposition of assets	—			—		(1,342		)	—
Net periodic benefit cost	$	8,385		$	244	$	8,113		$	293

The service component of our net periodic benefit costs is presented in operating expense and G&A expense, and the non-service components are presented in other (income) expense in our consolidated statements of income.

The changes in accumulated other comprehensive loss (“AOCL”) related to employee benefit plan assets and benefit obligations for the three months ended March 31, 2019 and 2020 were as follows (in thousands):



	Three Months Ended						Three Months Ended
	March 31, 2019						March 31, 2020
Gains (Losses) Included in AOCL	Pension Benefits			Other Postretirement Benefits			Pension Benefits			Other Postretirement Benefits
Beginning balance	$	(88,602	)	$	(5,409	)	$	(104,739	)	$	(8,378	)
Net actuarial loss	—			—			(747		)	—
Curtailment gain	—			—			1,703			—
Recognition of prior service credit amortization in income	(45		)	—			(45		)	—
Recognition of actuarial loss amortization in income	1,277			71			1,412			119
Recognition of settlement cost in income	—			—			969			—
Ending balance	$	(87,370	)	$	(5,338	)	$	(101,447	)	$	(8,259	)

Contributions estimated to be paid into the plans in 2020 are $31.4 million and $0.7 million for the pension plans and other postretirement benefit plan, respectively.