Impact of Reorganization Adjustments (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
	Apr. 01, 2017	Apr. 01, 2017	Dec. 31, 2016
Fresh-Start Adjustment [Line Items]
Total pre-tax gain on plan effects, see also (j) below	$ 3,031.2
Successor debt issuance costs and other items, see also (f) and (g) above	50.9	$ 50.9
Net impact on accumulated deficit	5,134.3	5,134.3
Predecessor
Fresh-Start Adjustment [Line Items]
Total pre-tax gain on plan effects, see also (j) below		3,031.2	$ 0.0
Cancellation of Predecessor Common Stock	0.2	0.2
Cancellation of Predecessor Additional paid-in capital	2,423.9	2,423.9
Cancellation of Predecessor Treasury stock	$ (371.9)	$ (371.9)