Supplemental Guarantor Information (Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 82.4	$ 76.2	$ 63.6	$ 54.4
Accounts receivable, net	287.8	242.6
Inventories, net	304.8	282.8
Receivable from affiliates	20.0	18.4
Other current assets	86.9	60.9
Total current assets	781.9	680.9
Investments in subsidiaries	0.0	0.0
Intercompany advances	0.0	0.0
Property, plant and equipment, net	200.8	179.5
Goodwill	102.1	100.2
Intangible assets, net	103.9	99.5
Other long-term assets	86.5	86.2
Total assets	1,275.2	1,146.3
Current liabilities:
Trade accounts payable	183.9	173.7
Payable to affiliates	7.1	7.1
Current portion of long-term debt and short-term debt	15.6	17.7
Accrued expenses and other	100.6	86.0
Total current liabilities	307.2	284.5
Long-term liabilities, less current portion:
Debt	591.9	515.5
Deferred income taxes	28.8	23.6
Other long-term liabilities	31.0	30.7
Total long-term liabilities	651.7	569.8
Intercompany advances	0.0	0.0
Total Park-Ohio Industries, Inc. and Subsidiaries shareholder's equity	303.6	279.9
Noncontrolling interests	12.7	12.1
Total equity	316.3	292.0
Total liabilities and shareholder's equity	1,275.2	1,146.3
Reportable Legal Entities | Parent
Current assets:
Cash and cash equivalents	0.0	0.0	0.0	0.0
Accounts receivable, net	0.0	0.0
Inventories, net	0.0	0.0
Receivable from affiliates	0.0	0.6
Other current assets	1.8	0.9
Total current assets	1.8	1.5
Investments in subsidiaries	582.4	512.3
Intercompany advances	373.4	364.8
Property, plant and equipment, net	5.8	6.0
Goodwill	0.0	0.0
Intangible assets, net	0.0	0.0
Other long-term assets	75.0	72.0
Total assets	1,038.4	956.6
Current liabilities:
Trade accounts payable	0.0	0.0
Payable to affiliates	0.0	0.0
Current portion of long-term debt and short-term debt	0.0	0.0
Accrued expenses and other	11.6	12.4
Total current liabilities	11.6	12.4
Long-term liabilities, less current portion:
Debt	530.3	455.3
Deferred income taxes	0.0	0.0
Other long-term liabilities	24.8	25.3
Total long-term liabilities	555.1	480.6
Intercompany advances	155.4	171.6
Total Park-Ohio Industries, Inc. and Subsidiaries shareholder's equity	303.6	279.9
Noncontrolling interests	12.7	12.1
Total equity	316.3	292.0
Total liabilities and shareholder's equity	1,038.4	956.6
Reportable Legal Entities | Combined Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	2.1	0.2	0.0	0.0
Accounts receivable, net	193.3	149.5
Inventories, net	223.4	198.9
Receivable from affiliates	0.0	0.0
Other current assets	43.5	34.8
Total current assets	462.3	383.4
Investments in subsidiaries	338.8	267.4
Intercompany advances	87.3	85.2
Property, plant and equipment, net	117.1	103.5
Goodwill	64.0	58.9
Intangible assets, net	64.6	60.0
Other long-term assets	4.3	3.4
Total assets	1,138.4	961.8
Current liabilities:
Trade accounts payable	128.9	121.8
Payable to affiliates	0.0	0.0
Current portion of long-term debt and short-term debt	5.6	9.0
Accrued expenses and other	41.5	32.7
Total current liabilities	176.0	163.5
Long-term liabilities, less current portion:
Debt	13.2	9.3
Deferred income taxes	20.7	15.5
Other long-term liabilities	1.2	1.2
Total long-term liabilities	35.1	26.0
Intercompany advances	376.2	289.5
Total Park-Ohio Industries, Inc. and Subsidiaries shareholder's equity	551.1	482.8
Noncontrolling interests	0.0	0.0
Total equity	551.1	482.8
Total liabilities and shareholder's equity	1,138.4	961.8
Reportable Legal Entities | Combined Non-Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	80.3	76.0	63.6	54.4
Accounts receivable, net	94.5	93.1
Inventories, net	81.4	83.9
Receivable from affiliates	20.0	17.8
Other current assets	41.6	25.2
Total current assets	317.8	296.0
Investments in subsidiaries	0.0	0.0
Intercompany advances	200.3	112.9
Property, plant and equipment, net	77.9	70.0
Goodwill	38.1	41.3
Intangible assets, net	39.3	39.5
Other long-term assets	7.2	10.8
Total assets	680.6	570.5
Current liabilities:
Trade accounts payable	55.0	51.9
Payable to affiliates	7.1	7.1
Current portion of long-term debt and short-term debt	10.0	8.7
Accrued expenses and other	47.5	40.9
Total current liabilities	119.6	108.6
Long-term liabilities, less current portion:
Debt	48.4	50.9
Deferred income taxes	8.1	8.1
Other long-term liabilities	5.0	4.2
Total long-term liabilities	61.5	63.2
Intercompany advances	129.4	101.8
Total Park-Ohio Industries, Inc. and Subsidiaries shareholder's equity	357.4	284.8
Noncontrolling interests	12.7	12.1
Total equity	370.1	296.9
Total liabilities and shareholder's equity	680.6	570.5
Reclassifications/ Eliminations
Current assets:
Cash and cash equivalents	0.0	0.0	$ 0.0	$ 0.0
Accounts receivable, net	0.0	0.0
Inventories, net	0.0	0.0
Receivable from affiliates	0.0	0.0
Other current assets	0.0	0.0
Total current assets	0.0	0.0
Investments in subsidiaries	(921.2)	(779.7)
Intercompany advances	(661.0)	(562.9)
Property, plant and equipment, net	0.0	0.0
Goodwill	0.0	0.0
Intangible assets, net	0.0	0.0
Other long-term assets	0.0	0.0
Total assets	(1,582.2)	(1,342.6)
Current liabilities:
Trade accounts payable	0.0	0.0
Payable to affiliates	0.0	0.0
Current portion of long-term debt and short-term debt	0.0	0.0
Accrued expenses and other	0.0	0.0
Total current liabilities	0.0	0.0
Long-term liabilities, less current portion:
Debt	0.0	0.0
Deferred income taxes	0.0	0.0
Other long-term liabilities	0.0	0.0
Total long-term liabilities	0.0	0.0
Intercompany advances	(661.0)	(562.9)
Total Park-Ohio Industries, Inc. and Subsidiaries shareholder's equity	(908.5)	(767.6)
Noncontrolling interests	(12.7)	(12.1)
Total equity	(921.2)	(779.7)
Total liabilities and shareholder's equity	$ (1,582.2)	$ (1,342.6)