Commitments and Contingencies - Narrative (Details) € in Millions, $ in Millions						1 Months Ended		9 Months Ended	12 Months Ended
	May 29, 2020 USD ($)	Mar. 03, 2020 USD ($)	Mar. 15, 2019 USD ($)	Mar. 11, 2019 EUR (€)	Aug. 03, 2016 EUR (€)	Jun. 30, 2020 USD ($)	Jan. 31, 2013	Sep. 30, 2020 EUR (€) company subsidiary	Mar. 18, 2019 USD ($)	Sep. 30, 2020 USD ($)
Loss Contingencies [Line Items]
Off-balance sheet arrangements										$ 4,100.0
Administrative enforcement order
Loss Contingencies [Line Items]
Value of alleged damages sought						$ 0.7
Pending litigation | Equipment failure | Natural Gas Storage System in Northern Germany
Loss Contingencies [Line Items]
Value of alleged damages sought | €				€ 142	€ 202
Marginal rate on annual prime rate (percent)				5.00%	5.00%
Pending litigation | Damage from fire | INOES and Naphtachimie
Loss Contingencies [Line Items]
Value of alleged damages sought | €								€ 250
Plant shutdown days							15 days
Subsidiaries participating | subsidiary								2
Other companies participating | company								17
Pending litigation | Breach of contract | International Engineering & Construction S.A. (IEC)
Loss Contingencies [Line Items]
Value of alleged damages sought			$ 591.0
Pending litigation | Loss of cash flow | International Engineering & Construction S.A. (IEC)
Loss Contingencies [Line Items]
Value of alleged damages sought		$ 700.0
Pending litigation | Lost profits and various costs | International Engineering & Construction S.A. (IEC)
Loss Contingencies [Line Items]
Value of alleged damages sought	$ 235.0	244.9
Pending litigation | Liquidated damages | International Engineering & Construction S.A. (IEC)
Loss Contingencies [Line Items]
Value of alleged damages sought		4.8
Pending litigation | Take-or-pay future obligations | International Engineering & Construction S.A. (IEC)
Loss Contingencies [Line Items]
Value of alleged damages sought		$ 58.6
Pending litigation | Legal fees | International Engineering & Construction S.A. (IEC)
Loss Contingencies [Line Items]
Value of alleged damages sought	$ 14.2
Pending litigation | Breach of fiduciary duties | Shareholder derivative lawsuits
Loss Contingencies [Line Items]
Repurchase of stock from GE									$ 1,500.0
GE sale of stock									$ 2,500.0