Basis of Presentation and Significant Accounting Policies - Allowance for Doubtful Accounts Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Doubtful Accounts Receivable [Roll Forward]
Beginning balance	$ 9.8	$ 3.5	$ 0.6
Provision, charged to expense	12.9	6.9	2.6
Write-offs, less recoveries, and other adjustments	(5.8)	(0.6)	0.3
Ending balance	$ 16.9	$ 9.8	$ 3.5