Employee benefit plans

3 Months Ended

Mar. 31, 2019

Retirement Benefits [Abstract]

Pension and other postretirement benefit plans

Employee benefit plans

Pension and other postretirement plans

The Company has noncontributory qualified defined benefit pension plans and other postretirement benefit plans for certain eligible employees. Components of net periodic benefit cost (credit) for the Company's pension and other postretirement benefit plans were as follows:

	Pension Benefits						Other Postretirement Benefits
Three Months Ended March 31,	2019			2018			2019			2018
	(In thousands)
Components of net periodic benefit cost (credit):
Service cost	$	—		$	—		$	344		$	407
Interest cost	3,773			3,807			780			778
Expected return on assets	(5,120		)	(4,998		)	(1,220		)	(1,167		)
Amortization of prior service credit	—			—			(252		)	(349		)
Amortization of net actuarial loss	1,355			1,782			—			238
Net periodic benefit cost (credit), including amount capitalized	8			591			(348		)	(93		)
Less amount capitalized	—			—			31			40
Net periodic benefit cost (credit)	$	8		$	591		$	(379	)	$	(133	)

The components of net periodic benefit cost (credit), other than the service cost component, are included in other income on the Consolidated Statements of Income. The service cost component is included in operation and maintenance expense on the Consolidated Statements of Income.

Nonqualified defined benefit plans

In addition to the qualified defined benefit pension plans reflected in the table at the beginning of this note, the Company also has unfunded, nonqualified defined benefit plans for executive officers and certain key management employees that generally provide for defined benefit payments at age 65 following the employee's retirement or, upon death, to their beneficiaries for a 15-year period. In February 2016, the Company froze the unfunded, nonqualified defined benefit plans to new participants and eliminated benefit increases. Vesting for participants not fully vested was retained. The Company's net periodic benefit cost for these plans was $1.1 million and $1.1 million for the three months ended March 31, 2019 and 2018, respectively. The components of net periodic benefit cost for these plans, which does not contain any service costs, are included in other income on the Consolidated Statements of Income.