Unconsolidated Affiliates (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement Data:
Revenues	$ 1,248.6	$ 1,225.7	$ 1,247.3
Costs and expenses	1,192.4	1,132.7	1,188.2
Net income	56.2	93.0	$ 59.1
Balance Sheet Data:
Current assets	570.2	515.2
Noncurrent assets	823.8	823.5
Current liabilities	423.0	313.0
Noncurrent liabilities	396.6	444.0
Partners’ and stockholders’ equity	$ 574.4	$ 581.7