Employee Retirement Plans (Tables)

3 Months Ended

Mar. 31, 2018

Employee Retirement Plans [Abstract]

Net Periodic Benefit Expense

	Pension Benefits				Postretirement benefits
	Three months ended				Three months ended
	March 31,				March 31,
	2018		2017		2018		2017
Service cost	$	25	$	24	$	3	$	3
Interest cost		32		31		6		7
Expected return on plan assets		(47)		(43)
Amortization of prior service    cost (credit)		2		1		(1)		(1)
Total pension and postretirement    benefit expense	$	12	$	13	$	8	$	9