Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Income Tax Contingency [Line Items]
Effective income tax rate percentage	(116.00%)	37.00%	(39.00%)	46.00%
Net discrete tax expense (benefit)	$ 138.4	$ (9.0)	$ 220.5	$ (1.6)
Deferred tax benefit related to recognition of deferred tax asset related to company's equity investment in certain foreign subsidiary			140.4
Deferred tax benefit related to recognition of deferred tax asset related to company's equity investment in certain foreign subsidiary, gross			235.0
Deferred tax expense (benefit) related to valuation allowance established for deferred tax assets			95.0	(15.7)
Net current tax benefit recognized for resolution of uncertain tax position taken in prior year income tax returns			19.3
Deferred tax benefit on debt extinguishment costs			65.2
Miscellaneous other tax (benefit) expense items		$ 6.7	2.6	0.2
Favorable reduction in certain tax reserves				$ 13.9
Liability for uncertain tax positions	13.7		13.7		$ 36.4
Net reduction			22.7
Accrual for interest and penalties	7.3		7.3		$ 11.7
NACCO Subsidiaries | Assets Held-For-Sale (AHFS)
Income Tax Contingency [Line Items]
Deferred tax benefit for disposition of investments			6.9
CIT Commercial Air Business | Discontinued Operations, Disposed of by Sale
Income Tax Contingency [Line Items]
Deferred tax expense related to restructuring of legal entities in preparation for Commercial Air sale			13.9
Net reduction			4.9
Maximum
Income Tax Contingency [Line Items]
Potential decrease to tax benefits	5.0		5.0
Non U.S.
Income Tax Contingency [Line Items]
Deferred tax assets, valuation allowance	30.0		30.0
U.S. State
Income Tax Contingency [Line Items]
Deferred tax assets, valuation allowance	$ 240.0		240.0
Net reduction related to decrease from favorable tax actions			$ 15.7