Financial Statements for Guarantors of the Senior Notes - Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets:
Cash and cash equivalents	$ 179.2	$ 778.6	$ 741.6	$ 981.8
Short-term marketable securities	0.0	319.5
Receivables, net of allowance	276.6	204.4
Income tax receivable	40.4	24.0
Inventory	524.7	402.8
Property, plant, and equipment, net	6,334.4	5,557.8
Investments in and advances to subsidiaries	0.0	0.0
Restricted cash	171.6	195.2
Goodwill and other assets	462.3	406.7
Disposal Group, Including Discontinued Operation, Assets	0.0	1,654.2
Total assets	7,989.2	9,543.2
Liabilities:
Accounts payable	212.1	119.5
Accrued liabilities	368.3	321.9
Total debt	4,029.2	3,241.9
Deferred income	17.7	20.5
Deferred income taxes	743.1	728.3
Advances from subsidiaries	0.0	0.0
Disposal Group, Including Discontinued Operation, Liabilities	0.0	198.4
Other liabilities	56.8	54.7
Total stockholders' equity	2,562.0	4,858.0	4,311.1	4,048.7
Total liabilities and stockholders' equity	7,989.2	9,543.2
Reportable legal entities | Parent
Assets:
Cash and cash equivalents	154.7	763.9	537.9	768.3
Short-term marketable securities	0.0	319.5
Receivables, net of allowance	12.5	1.1
Income tax receivable	40.4	24.0
Inventory	0.0	0.0
Property, plant, and equipment, net	42.0	47.6
Investments in and advances to subsidiaries	4,557.8	5,845.4
Restricted cash	0.0	0.0
Goodwill and other assets	205.1	130.7
Disposal Group, Including Discontinued Operation, Assets		0.0
Total assets	5,012.5	7,132.2
Liabilities:
Accounts payable	8.6	7.2
Accrued liabilities	184.3	182.4
Total debt	397.4	838.1
Deferred income	0.0	0.0
Deferred income taxes	0.0	54.6
Advances from subsidiaries	1,803.4	1,137.4
Disposal Group, Including Discontinued Operation, Liabilities		0.0
Other liabilities	56.8	54.5
Total stockholders' equity	2,562.0	4,858.0
Total liabilities and stockholders' equity	5,012.5	7,132.2
Reportable legal entities | Combined Guarantor Subsidiaries
Assets:
Cash and cash equivalents	4.1	1.6	5.3	1.9
Short-term marketable securities	0.0	0.0
Receivables, net of allowance	144.9	134.5
Income tax receivable	0.0	0.0
Inventory	448.0	341.2
Property, plant, and equipment, net	1,371.9	2,161.1
Investments in and advances to subsidiaries	3,091.7	1,807.3
Restricted cash	0.0	0.0
Goodwill and other assets	186.9	189.8
Disposal Group, Including Discontinued Operation, Assets		0.0
Total assets	5,247.5	4,635.5
Liabilities:
Accounts payable	122.1	48.3
Accrued liabilities	51.5	47.4
Total debt	0.0	28.3
Deferred income	16.5	19.2
Deferred income taxes	790.5	675.2
Advances from subsidiaries	0.0	0.0
Disposal Group, Including Discontinued Operation, Liabilities		0.0
Other liabilities	0.0	0.0
Total stockholders' equity	4,266.9	3,817.1
Total liabilities and stockholders' equity	5,247.5	4,635.5
Reportable legal entities | Combined Non-Guarantor Subsidiaries
Assets:
Cash and cash equivalents	59.1	65.3	198.4	211.6
Short-term marketable securities	0.0	0.0
Receivables, net of allowance	119.2	68.8
Income tax receivable	0.0	0.0
Inventory	77.9	62.2
Property, plant, and equipment, net	5,644.1	3,865.8
Investments in and advances to subsidiaries	551.1	528.6
Restricted cash	132.9	143.0
Goodwill and other assets	118.0	88.6
Disposal Group, Including Discontinued Operation, Assets		1,654.2
Total assets	6,702.3	6,476.5
Liabilities:
Accounts payable	81.8	64.1
Accrued liabilities	132.6	92.7
Total debt	3,631.8	2,375.5
Deferred income	1.2	1.4
Deferred income taxes	0.0	0.0
Advances from subsidiaries	0.0	0.0
Disposal Group, Including Discontinued Operation, Liabilities		198.4
Other liabilities	0.0	0.2
Total stockholders' equity	2,854.9	3,744.2
Total liabilities and stockholders' equity	6,702.3	6,476.5
Eliminations
Assets:
Cash and cash equivalents	(38.7)	(52.2)	$ 0.0	$ 0.0
Short-term marketable securities	0.0	0.0
Receivables, net of allowance	0.0	0.0
Income tax receivable	0.0	0.0
Inventory	(1.2)	(0.6)
Property, plant, and equipment, net	(723.6)	(516.7)
Investments in and advances to subsidiaries	(8,200.6)	(8,181.3)
Restricted cash	38.7	52.2
Goodwill and other assets	(47.7)	(2.4)
Disposal Group, Including Discontinued Operation, Assets		0.0
Total assets	(8,973.1)	(8,701.0)
Liabilities:
Accounts payable	(0.4)	(0.1)
Accrued liabilities	(0.1)	(0.6)
Total debt	0.0	0.0
Deferred income	0.0	(0.1)
Deferred income taxes	(47.4)	(1.5)
Advances from subsidiaries	(1,803.4)	(1,137.4)
Disposal Group, Including Discontinued Operation, Liabilities		0.0
Other liabilities	0.0	0.0
Total stockholders' equity	(7,121.8)	(7,561.3)
Total liabilities and stockholders' equity	$ (8,973.1)	$ (8,701.0)