Other Balance Sheet Accounts - Other Current Assets (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Other Current Assets:
Non-trade receivables	$ 18.7	$ 19.9
Income tax receivable	32.3	10.6
Prepaid and other	18.2	12.4
Total other current assets	$ 69.2	$ 42.9