Pension Plan and Other Postretirement Benefits (Tables)

9 Months Ended

Sep. 30, 2019

Retirement Benefits [Abstract]

Schedule of components of net periodic benefit costs for the pension plans and other postretirement benefits

The following tables list components of net periodic benefit costs for the pension plans and other postretirement benefits. The data listed under “pension plan” includes the qualified pension plan and the non-qualified supplemental executive retirement plan. The data listed under “other benefits” is for all other postretirement benefits.

	Three Months Ended September 30
	Pension Plan						Other Benefits
	2019			2018			2019			2018
Service cost	$	6,910		$	6,966		$	2,082		$	1,966
Interest cost	6,941			6,007			1,407			1,183
Expected return on plan assets	(7,581		)	(7,052		)	(1,475		)	(1,397		)
Amortization of prior service cost	1,262			1,263			49			11
Recognized net actuarial loss	1,821			2,791			214			242
Net periodic benefit cost	$	9,353		$	9,975		$	2,277		$	2,005

	Nine Months Ended September 30
	Pension Plan						Other Benefits
	2019			2018			2019			2018
Service cost	$	20,039		$	21,770		$	5,606		$	7,066
Interest cost	20,225			17,996			4,081			4,152
Expected return on plan assets	(22,714		)	(20,777		)	(4,346		)	(4,229		)
Amortization of prior service cost	3,786			3,789			148			32
Recognized net actuarial loss	4,445			8,386			421			1,789
Net periodic benefit cost	$	25,781		$	31,164		$	5,910		$	8,810