Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Capitalized interest expense	$ 0.7	$ 1.1	$ 0.8
Interest	71.1	108.5	153.1
Income taxes, net of refunds	1.7	8.8	9.1
Noncash Investing and Financing Items [Abstract]
Acquisition of property by assuming debt and other financing arrangements	12.0	5.8	4.7
Acquisition of property on account	23.8	34.6	24.8
CyrusOne [Member]
Noncash Investing and Financing Items [Abstract]
Accrual of CyrusOne dividends	$ 1.1
CyrusOne [Member]
Noncash Investing and Financing Items [Abstract]
Accrual of CyrusOne dividends		$ 2.1	$ 6.0