Condensed Consolidated Statements of Operations - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Service revenues	$ 386.7	$ 384.0
Operating costs and expenses
Operating (exclusive of items shown separately below)	257.3	249.6
Selling, general and administrative	51.0	49.7
Depreciation and amortization	64.6	65.9
Acquisition and development costs	0.0	0.7
Loss on disposal of assets and asset impairments	0.1	0.2
Total operating costs and expenses	373.0	366.1
Operating income	13.7	17.9
Other (expense) income
Interest expense	(22.6)	(26.0)
Other income, net	0.6	0.7
Total other expense	(22.0)	(25.3)
Loss before income taxes	(8.3)	(7.4)
Income tax benefit	(2.0)	(1.4)
Net loss	$ (6.3)	$ (6.0)
Net loss attributable to common stockholders per share
Basic loss per share (in dollars per share)	$ (0.07)	$ (0.07)
Diluted loss per share (in dollars per share)	$ (0.07)	$ (0.07)
Basic average shares outstanding (in shares)	90,059,917	88,721,612
Diluted average shares outstanding (in shares)	90,059,917	88,721,612