Pension and Postretirement Benefits (Tables)

6 Months Ended

Jun. 30, 2017

General Discussion Of Pension And Other Postretirement Benefits [Abstract]

Schedule of Defined Benefit Plans Disclosures [Table Text Block]

	Three Months Ended June 30,								Six Months Ended June 30,
					Other								Other
					Postretirement								Postretirement
	Pension Benefits				Benefits				Pension Benefits				Benefits
		2017		2016		2017		2016		2017		2016		2017		2016
Service cost	$	871	$	683	$	1	$	4	$	1,789	$	1,353	$	4	$	8
Interest cost		1,003		1,122		39		39		2,011		2,233		72		78
Expected return on plan assets		(1,255)		(1,354)		—		—		(2,581)		(2,698)		—		—
Settlement charge		1,860		—		—		—		1,860		—		—		—
Actuarial loss amortization		792		812		22		15		1,661		1,620		27		30
Prior service cost amortization		(25)		(26)		—		—		(48)		(51)		—		—
Net periodic benefit cost	$	3,246	$	1,237	$	62	$	58	$	4,692	$	2,457	$	103	$	116