Financial Statements for Guarantors of the Senior Notes - Balance Sheet (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Assets:
Cash and cash equivalents	$ 73.9	$ 179.2
Receivables, net of allowance	370.0	276.6
Income tax receivable	16.1	40.4
Inventory	618.4	524.7
Property, plant, and equipment, net	6,746.8	6,334.4
Investments in and advances to subsidiaries	0.0	0.0
Restricted cash	114.2	171.6
Goodwill and other assets	474.5	462.3
Total assets	8,413.9	7,989.2
Liabilities:
Accounts payable	197.3	212.1
Accrued liabilities	336.3	368.3
Debt	4,466.4	4,029.2
Deferred income	0.0	17.7
Deferred income taxes	752.7	743.1
Advances from subsidiaries	0.0	0.0
Other liabilities	96.1	56.8
Total stockholders' equity	2,565.1	2,562.0	$ 4,834.6	$ 4,858.0
Total liabilities and stockholders' equity	8,413.9	7,989.2
Reportable legal entities | Parent
Assets:
Cash and cash equivalents	63.0	154.7
Receivables, net of allowance	18.5	12.5
Income tax receivable	16.1	40.4
Inventory	0.0	0.0
Property, plant, and equipment, net	40.8	42.0
Investments in and advances to subsidiaries	4,626.2	4,558.6
Restricted cash	0.0	0.0
Goodwill and other assets	219.0	205.1
Total assets	4,983.6	5,013.3
Liabilities:
Accounts payable	4.9	8.6
Accrued liabilities	152.9	184.3
Debt	647.5	397.4
Deferred income		0.0
Deferred income taxes	0.0	0.0
Advances from subsidiaries	1,559.7	1,804.2
Other liabilities	53.5	56.8
Total stockholders' equity	2,565.1	2,562.0
Total liabilities and stockholders' equity	4,983.6	5,013.3
Reportable legal entities | Combined Guarantor Subsidiaries
Assets:
Cash and cash equivalents	2.9	4.1
Receivables, net of allowance	250.0	181.8
Income tax receivable	0.0	0.0
Inventory	575.2	485.8
Property, plant, and equipment, net	1,608.5	1,436.3
Investments in and advances to subsidiaries	2,687.5	2,981.7
Restricted cash	0.0	0.0
Goodwill and other assets	238.5	197.9
Total assets	5,362.6	5,287.6
Liabilities:
Accounts payable	122.2	134.0
Accrued liabilities	46.1	55.4
Debt	0.0	0.0
Deferred income		16.5
Deferred income taxes	811.7	790.3
Advances from subsidiaries	0.0	0.0
Other liabilities	41.3	0.0
Total stockholders' equity	4,341.3	4,291.4
Total liabilities and stockholders' equity	5,362.6	5,287.6
Reportable legal entities | Combined Non-Guarantor Subsidiaries
Assets:
Cash and cash equivalents	35.0	59.1
Receivables, net of allowance	101.5	82.3
Income tax receivable	0.0	0.0
Inventory	45.7	40.9
Property, plant, and equipment, net	5,806.1	5,579.7
Investments in and advances to subsidiaries	701.7	661.1
Restricted cash	87.2	132.9
Goodwill and other assets	76.2	106.8
Total assets	6,853.4	6,662.8
Liabilities:
Accounts payable	70.6	69.9
Accrued liabilities	141.1	128.7
Debt	3,818.9	3,631.8
Deferred income		1.2
Deferred income taxes	0.0	0.0
Advances from subsidiaries	0.0	0.0
Other liabilities	1.3	0.0
Total stockholders' equity	2,821.5	2,831.2
Total liabilities and stockholders' equity	6,853.4	6,662.8
Eliminations
Assets:
Cash and cash equivalents	(27.0)	(38.7)
Receivables, net of allowance	0.0	0.0
Income tax receivable	0.0	0.0
Inventory	(2.5)	(2.0)
Property, plant, and equipment, net	(708.6)	(723.6)
Investments in and advances to subsidiaries	(8,015.4)	(8,201.4)
Restricted cash	27.0	38.7
Goodwill and other assets	(59.2)	(47.5)
Total assets	(8,785.7)	(8,974.5)
Liabilities:
Accounts payable	(0.4)	(0.4)
Accrued liabilities	(3.8)	(0.1)
Debt	0.0	0.0
Deferred income		0.0
Deferred income taxes	(59.0)	(47.2)
Advances from subsidiaries	(1,559.7)	(1,804.2)
Other liabilities	0.0	0.0
Total stockholders' equity	(7,162.8)	(7,122.6)
Total liabilities and stockholders' equity	$ (8,785.7)	$ (8,974.5)