Investments in Affiliated Companies (Summarized Financial Data-RRPF) (Details 6) $ in Millions		12 Months Ended
		Dec. 31, 2018 USD ($) AircraftEngines	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Schedule of Equity Method Investments [Line Items]
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment		$ 3,015.7	$ 2,853.3
Income Statement [Abstract]
Lease revenue		458.8	350.7	$ 333.7
Net income		120.5	100.4	99.3
Assets [Abstract]
Current assets		306.6	144.8
Other noncurrent assets		4,428.7	3,847.2
Total assets		4,735.3	3,992.0
Liabilities and Equity [Abstract]
Current liabilities		830.6	446.8
Long-term debt		3,013.0	2,704.9
Shareholders’ equity		891.7	840.3
Total liabilities and shareholders' equity		4,735.3	3,992.0
Rolls Royce Partners Finance [Member]
Income Statement [Abstract]
Income taxes				(7.8)
RRPF Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment		$ 1,024.7	943.5
Number of Aircraft Engines | AircraftEngines		452
Income Statement [Abstract]
Depreciation expense		$ (195.6)	(176.4)	(171.6)
Interest expense		(94.3)	(64.3)	(59.2)
Other expenses		(28.1)	(8.9)	(8.0)
Gains on sales of assets		6.1	20.5	19.1
Income before income taxes		121.3	115.7	104.2
Income taxes	[1]	(18.1)	(13.2)	(6.9)
Net income		103.2	102.5	97.3
Assets [Abstract]
Current assets		304.7	135.3
Operating assets, net of accumulated depreciation of $744.5 and $651.8	[2]	4,428.7	3,772.4
Total assets		4,733.4	3,907.7
EquityMethodInvestmentSummarizedFinancialInformationAPandAccruedExpense		97.9	53.9
Liabilities and Equity [Abstract]
Current liabilities		732.1	392.0
Long-term debt		2,733.6	2,359.1
Other liabilities		279.4	274.1
Shareholders’ equity		890.4	828.6
Total liabilities and shareholders' equity		4,733.4	3,907.7
RRPF Joint Ventures [Member] | Third Parties [Member]
Income Statement [Abstract]
Lease revenue		200.5	168.8	173.7
RRPF Joint Ventures [Member] | Rolls Royce [Member]
Income Statement [Abstract]
Lease revenue		$ 232.7	$ 176.0	$ 150.2

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[2] (a) All operating assets were pledged as collateral for long-term debt obligations.