Employee Benefit Plans - Weighted-Average Assumptions, Pension Plans (Details) - Pension Plans	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
United States
Summary of weighted-average actuarial assumptions used in determining annual pension expense
Discount rate	3.70%	4.20%	4.50%
Rate of increase in compensation levels	3.00%	3.00%	3.00%
Expected long-term rate of return on plan assets	5.40%	5.40%	5.85%
Gain and loss amortization period (years)	21 years	21 years	23 years
Foreign Plan
Summary of weighted-average actuarial assumptions used in determining annual pension expense
Discount rate	2.70%	3.90%	3.70%
Rate of increase in compensation levels	3.08%	3.10%	3.10%
Expected long-term rate of return on plan assets	5.50%	5.48%	5.44%
Gain and loss amortization period (years)	26 years	26 years	27 years