Income Taxes - Schedule of Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Deferred compensation plans	$ 6.5	$ 10.7
Deferred income	4.7	4.3
Allowance for uncollectible receivables	0.8	1.2
Deferred liabilities	2.1	3.0
Net operating losses and credit carryforward	5.1	8.1
Deferred tax assets	19.2	27.3
Valuation allowance	(0.2)	(0.4)
Net deferred tax asset	19.0	26.9
Deferred tax liabilities:
Intangible assets in excess of tax basis	29.2	41.2
Property and equipment in excess of tax basis	22.4	34.8
Equity investments in excess of tax basis	6.8	11.1
Other	1.2	3.0
Deferred tax liabilities	59.6	90.1
Net deferred tax liability	$ (40.6)	$ (63.2)