Other Current Assets & Other Current Liabilities - Other Current Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Other Current Assets and Other Current Liabilities [Abstract]
Warranty accruals	$ 373.4	$ 321.3
Contingencies related to completed contracts	234.6	214.9
Provisions	216.1	223.0
Social security liability	139.3	145.0
Redeemable financial liability	124.2	69.7
Other taxes payable	216.8	204.4
Compensation accrual	63.1	123.5
Current accounts on contracts under joint arrangements	23.8	23.5
Liabilities held for sale	12.8	13.7
Current portion of accrued pension and other post-retirement benefits	10.4	10.3
Other accrued liabilities	427.6	338.6
Total other current liabilities	$ 1,842.1	$ 1,687.9