Income Taxes Net deferred income tax asset (liability) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Jun. 27, 2015
Deferred income tax asset (liability):
Depreciation and amortization	$ (765.2)	$ (1,550.6)	$ (1,618.1)
Inventory basis differences	27.4	22.8	32.6
Accrued liabilities	68.5	50.8	69.3
Allowance for doubtful accounts	1.7	1.3	0.9
Research and development	61.7	63.7	62.8
Loss carryforwards	292.4	244.2	232.4
Share-based compensation	18.1	20.6	14.3
Foreign tax credit	10.6	10.6	10.6
Federal benefit of unrecognized tax positions	24.3	22.8	26.3
Interest carryforwards	435.3	334.6	259.7
Other, net	3.0	14.7	30.1
Deferred tax asset	177.8
Subtotal		(764.5)	(879.1)
Valuation allowance	(495.6)	(536.8)	(516.6)
Net deferred income tax asset (liability):	$ (317.8)	$ (1,301.3)	$ (1,395.7)