Financing Arrangements (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2015
Line of Credit Facility [Line Items]
Percentage ownership	100.00%
Total debt		$ 581,700,000	$ 568,500,000
Southwest Steel Processing LLC | Arkansas Development Finance Authority
Line of Credit Facility [Line Items]
Maximum borrowing capacity					$ 11,000,000.0
Amount drawn		8,100,000
Machinery and Equipment
Line of Credit Facility [Line Items]
Finance lease obligations		$ 17,900,000
Maximum
Line of Credit Facility [Line Items]
Capital lease obligations					$ 50,000,000.0
Revolving credit facility
Line of Credit Facility [Line Items]
Stated interest rate		2.12%
Total debt		$ 188,200,000	173,200,000
Industrial Equipment Group European Facilities
Line of Credit Facility [Line Items]
Stated interest rate		3.25%
Total debt		$ 4,500,000	$ 4,600,000
Industrial Equipment Group European Facilities | Line of Credit | Banco Bolbao Vizcaya Argentaria, S.A.
Line of Credit Facility [Line Items]
Maximum borrowing capacity		27,400,000.0
Financing Agreement | Revolving credit facility | Line of Credit | Banco Bolbao Vizcaya Argentaria, S.A.
Line of Credit Facility [Line Items]
Maximum borrowing capacity		11,000,000
Amount drawn		0
Park-Ohio Industries, Inc. | Seventh Amendment Credit Agreement | Revolving credit facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 350,000,000.0
Park-Ohio Industries, Inc. | Seventh Amendment Credit Agreement | Revolving Credit Facility Canadian Sub-Limit
Line of Credit Facility [Line Items]
Maximum borrowing capacity	35,000,000.0
Park-Ohio Industries, Inc. | Seventh Amendment Credit Agreement | Revolving Credit Facility European Sub-Limit
Line of Credit Facility [Line Items]
Maximum borrowing capacity	25,000,000.0
Park-Ohio Industries, Inc. | Amendment No. 1 to Seventh Amended and Restated Credit Agreement | Revolving credit facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity				$ 375,000,000.0
Increase in additional borrowing capacity		100,000,000.0
Bank guarantees outstanding		$ 31,500,000		33,800,000
Park-Ohio Industries, Inc. | Amendment No. 1 to Seventh Amended and Restated Credit Agreement | Revolving Credit Facility Canadian Sub-Limit
Line of Credit Facility [Line Items]
Maximum borrowing capacity				40,000,000.0
Park-Ohio Industries, Inc. | Amendment No. 1 to Seventh Amended and Restated Credit Agreement | Revolving Credit Facility European Sub-Limit
Line of Credit Facility [Line Items]
Maximum borrowing capacity				$ 30,000,000.0
Park-Ohio Industries, Inc. | Senior Notes Due 2027 | Senior Notes
Line of Credit Facility [Line Items]
Aggregate principal amount	$ 350,000,000.0
Stated interest rate	6.625%