Derivatives and Fair Value Measurements - Gains and Losses on Hedging Derivatives (Details) - Designated as Hedging Instrument - USD ($) $ in Millions		3 Months Ended				6 Months Ended	9 Months Ended
		Sep. 30, 2017	Apr. 01, 2017	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2016
Predecessor
Derivative Instruments, Gain (Loss) [Line Items]
Total loss recognized in income			$ (27.6)	$ (47.4)			$ (272.9)
Loss reclassified from other comprehensive loss into income			(27.6)	(47.4)			(188.5)	[1]
(Loss) gain realized in income on derivatives			0.0	0.0			(84.4)
Unrealized gain (loss) recognized in income on non- designated derivatives			0.0	0.0			0.0
Predecessor | Fuel contracts
Derivative Instruments, Gain (Loss) [Line Items]
Loss reclassified from other comprehensive loss into income					$ 9.0
Predecessor | Commodity swap contracts | Operating costs and expenses
Derivative Instruments, Gain (Loss) [Line Items]
Total loss recognized in income			(11.0)	(19.4)			(78.3)
Loss reclassified from other comprehensive loss into income			(11.0)	(19.4)			(66.4)	[1]
(Loss) gain realized in income on derivatives			0.0	0.0			(11.9)
Unrealized gain (loss) recognized in income on non- designated derivatives			0.0	0.0			0.0
Predecessor | Commodity swap contracts | Reorganization items, net
Derivative Instruments, Gain (Loss) [Line Items]
Total loss recognized in income							(38.8)
Loss reclassified from other comprehensive loss into income	[1]						0.0
(Loss) gain realized in income on derivatives							(38.8)
Unrealized gain (loss) recognized in income on non- designated derivatives							0.0
Predecessor | Foreign currency cash flow hedge contracts
Derivative Instruments, Gain (Loss) [Line Items]
Loss reclassified from other comprehensive loss into income					$ 13.6
Predecessor | Foreign currency cash flow hedge contracts | Operating costs and expenses
Derivative Instruments, Gain (Loss) [Line Items]
Total loss recognized in income			(16.6)	(28.0)			(119.4)
Loss reclassified from other comprehensive loss into income			(16.6)	(28.0)			(122.1)	[1]
(Loss) gain realized in income on derivatives			0.0	0.0			2.7
Unrealized gain (loss) recognized in income on non- designated derivatives			$ 0.0	$ 0.0			0.0
Predecessor | Foreign currency cash flow hedge contracts | Reorganization items, net
Derivative Instruments, Gain (Loss) [Line Items]
Total loss recognized in income							(36.4)
Loss reclassified from other comprehensive loss into income	[1]						0.0
(Loss) gain realized in income on derivatives							(36.4)
Unrealized gain (loss) recognized in income on non- designated derivatives							$ 0.0
Successor
Derivative Instruments, Gain (Loss) [Line Items]
Total loss recognized in income		$ 5.6				$ 8.5
(Loss) gain realized in income on derivatives		7.3				7.0
Unrealized gain (loss) recognized in income on non- designated derivatives		(1.7)				1.5
Successor | Commodity swap contracts | Reorganization items, net
Derivative Instruments, Gain (Loss) [Line Items]
Total loss recognized in income		5.6
(Loss) gain realized in income on derivatives		7.3
Unrealized gain (loss) recognized in income on non- designated derivatives		$ (1.7)
Successor | Foreign currency cash flow hedge contracts | Operating costs and expenses
Derivative Instruments, Gain (Loss) [Line Items]
Total loss recognized in income						8.5
(Loss) gain realized in income on derivatives						7.0
Unrealized gain (loss) recognized in income on non- designated derivatives						$ 1.5

[1] Includes the reclassification from “Accumulated other comprehensive income (loss)” into earnings of $13.6 million and $9.0 million of previously unrecognized losses on foreign currency and fuel contracts, respectively, monetized in the first quarter of 2016.