Equity - Reclassification Out of Accumulated Other Comprehensive Income (Details) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Costs of sales and services	$ 656.0	$ 379.8
Selling, general and administrative expenses	200.4	114.3
Total before tax	331.8	54.4
Provision for income taxes	(68.7)	(9.4)
Net income (loss)	269.6	(123.8)
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)	(3.4)	(4.4)
Reclassification out of Accumulated Other Comprehensive Income | Derivative instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	(0.5)	0.7
Provision for income taxes	0.1	(0.2)
Net income (loss)	(0.4)	0.5
Reclassification out of Accumulated Other Comprehensive Income | Amortization of prior service costs
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Selling, general and administrative expenses	(0.1)	(0.2)
Reclassification out of Accumulated Other Comprehensive Income | Amortization of unrecognized net actuarial and other gains (losses)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Selling, general and administrative expenses	(3.6)	(3.4)
Reclassification out of Accumulated Other Comprehensive Income | Recognized loss due to curtailment and settlement
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Selling, general and administrative expenses	(0.9)	(3.9)
Reclassification out of Accumulated Other Comprehensive Income | Pension and other postretirement benefits
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	(4.6)	(7.5)
Provision for income taxes	1.6	2.6
Net income (loss)	(3.0)	(4.9)
Reclassification out of Accumulated Other Comprehensive Income | Foreign currency contracts | Derivative instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Costs of sales and services	(1.9)	(2.5)
Selling, general and administrative expenses	1.4	2.3
Reclassification out of Accumulated Other Comprehensive Income | Energy contracts | Derivative instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Costs of sales and services	$ 0.0	$ 0.9