Pension and Postretirement Benefits (Tables)

9 Months Ended

Sep. 30, 2017

General Discussion Of Pension And Other Postretirement Benefits [Abstract]

Schedule of Defined Benefit Plans Disclosures [Table Text Block]

	Three Months Ended September 30,								Nine Months Ended September 30,
					Other								Other
					Postretirement								Postretirement
	Pension Benefits				Benefits				Pension Benefits				Benefits
		2017		2016		2017		2016		2017		2016		2017		2016
Service cost	$	921	$	672	$	2	$	—	$	2,710	$	2,025	$	6	$	8
Interest cost		994		1,111		36		28		3,005		3,344		108		106
Expected return on plan assets		(1,276)		(1,329)		—		—		(3,857)		(4,027)		—		—
Settlement charge		—		—		—		—		1,860		—		—		—
Actuarial loss (gain) amortization		798		769		13		(30)		2,459		2,389		40		—
Prior service cost amortization		(28)		(25)		—		—		(76)		(76)		—		—
Net periodic benefit cost	$	1,409	$	1,198	$	51	$	(2)	$	6,101	$	3,655	$	154	$	114