Income Taxes (Effective Tax Rate Reconciliation) (Details)	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
U.S. federal statutory tax rate	35.00%	21.00%	24.50%	35.00%	35.00%
State taxes, net of federal benefit			1.00%	1.00%	1.20%
Income from equity affiliates			(2.10%)	(2.00%)	(3.30%)
Foreign tax differentials			(1.00%)	(7.90%)	(6.60%)
Tax on foreign repatriated earnings			(0.40%)	(2.20%)	(3.10%)
Domestic production activities			(0.40%)	(0.80%)	(0.80%)
Share-based compensation			(1.00%)	(1.20%)	0.00%
Tax reform repatriation			0.195	0	0
Tax reform rate change and other			(11.10%)	0.00%	0.00%
Tax restructuring benefit			(0.018)	0	0
Non-deductible goodwill impairment charge			0.00%	3.60%	0.00%
Non-U.S. subsidiary tax election			0.00%	(7.70%)	0.00%
Business separation costs			0.00%	0.20%	4.20%
Other			(1.20%)	0.40%	1.20%
Effective Tax Rate			26.00%	18.40%	27.80%