Commitments and Contingencies - Narrative (Details)				3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended
	Jul. 09, 2019 USD ($)	Apr. 13, 2018 USD ($)	Feb. 28, 2017 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Sep. 30, 2020 USD ($) defendant claim	Dec. 31, 2019 USD ($)	Dec. 31, 2016 USD ($)	Sep. 18, 2017 USD ($)
Loss Contingencies [Line Items]
Insurance recoveries					$ 17,500,000
Estimated insurance recoveries	$ 10,000,000
Accrued liabilities
Loss Contingencies [Line Items]
Accrual for environmental matters						$ 1,211,000
Other Noncurrent Liabilities
Loss Contingencies [Line Items]
Accrual for environmental matters						29,352,000
Handy & Harman Ltd. (HNH)
Loss Contingencies [Line Items]
Accrual for environmental matters						$ 25,083,000
Settlement amount	$ 30,000,000
BNS Subsidiary
Loss Contingencies [Line Items]
Claims, litigation matters (in number of claims) | claim						30,000
BNS Subsidiary | Insurance Claims
Loss Contingencies [Line Items]
Accrual relating to open and active claims						$ 1,349,000	$ 1,349,000
OMG
Loss Contingencies [Line Items]
Settlement amount								$ 949,000
Accrual relating to open and active claims								$ 4,100,000
Minimum | BNS Subsidiary
Loss Contingencies [Line Items]
Loss contingency, number of defendants (in defendants) | defendant						100,000
Adjacent Parcel | Environmental and Other Matters
Loss Contingencies [Line Items]
Accrual increase				$ 14,000,000
Adjacent Parcel | Environmental and Other Matters | Minimum | Handy & Harman Ltd. (HNH)
Loss Contingencies [Line Items]
Environmental exit costs, additional loss			$ 10,500,000
Adjacent Parcel | Environmental and Other Matters | Maximum | Handy & Harman Ltd. (HNH)
Loss Contingencies [Line Items]
Environmental exit costs, additional loss			$ 17,500,000
Costs | Former Owner / Operator | Environmental and Other Matters
Loss Contingencies [Line Items]
Ownership responsibility for site investigation and remediation costs percentage allocation						75.00%
Costs | Hhem and HandH
Loss Contingencies [Line Items]
Accrual for environmental matters						$ 1,200,000
Investigation and remediation costs						$ 9,600,000
Costs | Hhem and HandH | Environmental and Other Matters
Loss Contingencies [Line Items]
Ownership responsibility for site investigation and remediation costs percentage allocation						25.00%
Payments						$ 1,000,000
Investigation and remediation costs						3,100,000
Camden | SLI
Loss Contingencies [Line Items]
Accrual for environmental matters						2,600,000
Counteroffer						300,000
Camden - Past And Future Expenses | SLI
Loss Contingencies [Line Items]
Damages claimed									$ 1,800,000
Wayne facility | SLI
Loss Contingencies [Line Items]
Accrual for environmental matters						$ 1,200,000
Selling, General and Administrative Expenses | Handy & Harman Ltd. (HNH)
Loss Contingencies [Line Items]
Litigation Settlement, Expense							$ 12,500,000
Preferred stock | Steel Connect, Inc (STCN)
Loss Contingencies [Line Items]
Stock acquired		$ 35,000,000