Income Taxes Income Tax Provision (Benefit) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Apr. 01, 2017	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2016
Successor
Current:
U.S. federal		$ (101.4)	$ (46.8)
Non-U.S.		40.4	29.8
State		(0.4)	(0.1)
Total current		(61.4)	(17.1)
Deferred:
U.S. federal		(85.1)	30.4
Non-U.S.		(14.5)	5.7
State		0.0	(0.6)
Total deferred		(99.6)	35.5
Total income tax provision (benefit)		$ (161.0)	$ 18.4
Predecessor
Current:
U.S. federal	$ (3.1)			$ (12.4)
Non-U.S.	8.3			14.4
State	(6.7)			0.5
Total current	(1.5)			2.5
Deferred:
U.S. federal	(101.0)			(82.1)
Non-U.S.	(160.4)			(12.8)
State	(0.9)			(2.1)
Total deferred	(262.3)			(97.0)
Total income tax provision (benefit)	$ (263.8)			$ (94.5)