- Additional Information (Details)	7 Months Ended	12 Months Ended
	Dec. 31, 2019 USD ($) option	Dec. 31, 2019 USD ($) option facility $ / h $ / Hour	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Number of Investment Options Holding Substantially All Pension Funds | option	8	8
Employer contributions		$ 16,600,000	$ 17,200,000	$ 16,600,000
Number of our manufacturing facilities participating in multiemployer defined benefit pension plans | facility		2
Multiemployer Plans, Withdrawal Obligation	$ 81,600,000	$ 81,600,000
Contribution rates | $ / Hour		4.0
Additional contribution, percent of contractual contribution rate	2.50%
USW
Defined Benefit Plan Disclosure [Line Items]
Contribution rates | $ / h		2.79
Maximum | Plan A [Member]
Defined Benefit Plan Disclosure [Line Items]
Funded Percentage Of Pension Protection Plan	65.00%	65.00%
Maximum | Plan B [Member]
Defined Benefit Plan Disclosure [Line Items]
Funded Percentage Of Pension Protection Plan	80.00%	80.00%
Minimum | Plan B [Member]
Defined Benefit Plan Disclosure [Line Items]
Funded Percentage Of Pension Protection Plan	65.00%	65.00%
Minimum | Plan C [Member]
Defined Benefit Plan Disclosure [Line Items]
Funded Percentage Of Pension Protection Plan	80.00%	80.00%
Pension Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Net loss expected to be recognized as component of net periodic benefit over the next fiscal year	$ (9,900,000)	$ (9,900,000)
Fair value of plan assets	$ 306,600,000	306,600,000	268,800,000	310,900,000
Employer contribution		500,000	500,000
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement		$ 0	0	0
Other Postretirement Employee Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Assumed health care cost trend rates used to determine the company's benefit obligations and expense	6.80%	6.80%
Assumed health care cost trend rates, graded rate	5.90%	5.90%
Expected year when trend rate to be reached		70 years
Fair value of plan assets	$ 0	$ 0	0	0
Employer contribution		7,000,000	7,000,000
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement		$ 0	0	0
Other Postretirement Employee Benefit Plans | Maximum
Defined Benefit Plan Disclosure [Line Items]
Assumed health care cost trend rate, graded	3.90%	3.90%
Assumed health care cost trend rates, graded rate	3.80%	3.80%
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contribution		$ 500,000
Other Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contribution		0
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 0	0
Fair Value, Inputs, Level 1 | Other Postretirement Employee Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets				20,000
Cost of Sales [Member]
Defined Benefit Plan Disclosure [Line Items]
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax		1,500,000	1,200,000
Selling, General and Administrative Expenses [Member]
Defined Benefit Plan Disclosure [Line Items]
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax		$ 1,000,000	$ 800,000	900,000
Non-operating expense [Member]
Defined Benefit Plan Disclosure [Line Items]
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax				$ 1,300,000