Retirement Plans (Tables)

9 Months Ended

Sep. 30, 2018

Defined Benefit Plan Disclosure [Line Items]

Benefit costs

Our pension costs, which primarily include costs for the qualified TRP and the non-qualified SERP, are presented in the following table (in thousands):

	Quarter ended Sept. 30,						Nine months ended Sept. 30,
	2018			2017			2018			2017
Service cost-benefits earned during the period	$	3		$	218		$	9		$	654
Interest cost on benefit obligation	5,721			5,990			15,945			17,971
Expected return on plan assets	(8,218		)	(6,580		)	(23,148		)	(19,741		)
Amortization of prior service cost	42			159			126			476
Amortization of actuarial loss	1,271			2,081			3,814			6,242
Pension payment timing related charges	1,198			—			7,498			—
Expense for company-sponsored retirement plans	$	17		$	1,868		$	4,244		$	5,602