Pension and Other Postretirement Employee Benefits (Tables)

6 Months Ended

Jun. 30, 2018

General Discussion Of Pension And Other Postretirement Benefits [Abstract]

Components of Net Periodic Cost (Benefit)

The following tables detail the components of net periodic cost (benefit) of our pension plans and other postretirement employee benefits (OPEB):

	Three Months Ended June 30,
	Pension						OPEB
(Dollars in thousands)	2018			2017			2018			2017
Service cost	$	2,178		$	1,515		$	99		$	4
Interest cost		4,390			3,967			381			310
Expected return on plan assets		(5,135	)		(4,601	)		—			—
Amortization of prior service cost (credit)		47			72			(2,220	)		(2,220	)
Amortization of actuarial loss		4,144			3,386			301			371
Net periodic cost (benefit)	$	5,624		$	4,339		$	(1,439	)	$	(1,535	)
	Six Months Ended June 30,
	Pension						OPEB
(Dollars in thousands)	2018			2017			2018			2017
Service cost	$	4,091		$	3,377		$	143		$	7
Interest cost		8,304			8,048			700			631
Expected return on plan assets		(9,843	)		(9,204	)		—			—
Amortization of prior service cost (credit)		93			144			(4,439	)		(4,439	)
Amortization of actuarial loss		8,294			7,242			656			769
Net periodic cost (benefit)	$	10,939		$	9,607		$	(2,940	)	$	(3,032	)

Schedule of Pension and OPEB Changes in Accumulated Other Comprehensive Loss

The following tables detail the pension and OPEB changes in accumulated other comprehensive loss on our Condensed Consolidated Balance Sheets, net of tax:

	Three Months Ended June 30, 2018
(Dollars in thousands)	Pension			OPEB			Total
Balance at March 31, 2018	$	121,293		$	(4,047	)	$	117,246
Amortization of defined benefit items, net of tax:1
Prior service credit (cost)		(35	)		1,643			1,608
Actuarial loss		(3,067	)		(223	)		(3,290	)
Total reclassification for the period		(3,102	)		1,420			(1,682	)
Balance at June 30, 2018	$	118,191		$	(2,627	)	$	115,564
	Three Months Ended June 30, 2017
(Dollars in thousands)	Pension			OPEB			Total
Balance at March 31, 2017	$	118,231		$	(8,071	)	$	110,160
Amortization of defined benefit items, net of tax:1
Prior service credit (cost)		(44	)		1,354			1,310
Actuarial loss		(2,066	)		(226	)		(2,292	)
Total reclassification for the period		(2,110	)		1,128			(982	)
Balance at June 30, 2017	$	116,121		$	(6,943	)	$	109,178

	Six Months Ended June 30, 2018
(Dollars in thousands)	Pension			OPEB			Total
Balance at December 31, 2017	$	100,611		$	(5,055	)	$	95,556
Amortization of defined benefit items, net of tax:1
Prior service credit (cost)		(69	)		3,285			3,216
Actuarial loss		(6,138	)		(485	)		(6,623	)
Total reclassification for the period		(6,207	)		2,800			(3,407	)
Amortization reclassified from AOCL2		23,787			(372	)		23,415
Balance at June 30, 2018	$	118,191		$	(2,627	)	$	115,564
	Six Months Ended June 30, 2017
(Dollars in thousands)	Pension			OPEB			Total
Balance at December 31, 2016	$	120,627		$	(9,182	)	$	111,445
Amortization of defined benefit items, net of tax:1
Prior service credit (cost)		(88	)		2,708			2,620
Actuarial loss		(4,418	)		(469	)		(4,887	)
Total reclassification for the period		(4,506	)		2,239			(2,267	)
Balance at June 30, 2017	$	116,121		$	(6,943	)	$	109,178

¹Amortization of prior service credit (cost) and amortization of actuarial loss are included in the computation of net periodic cost (benefit).