Balance Sheet Accounts - Schedule of Other Noncurrent Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Conditional asset retirement obligations	$ 30.7	$ 30.6
Pension benefits, non-qualified	17.4	17.5
Deferred compensation	21.4	19.8
Deferred revenue	13.1	13.3
Competitive improvement program obligations (see Note 10)	0.0	1.3
Uncertain income tax positions	29.3	28.4
Other	12.9	13.1
Other noncurrent liabilities	$ 124.8	$ 124.0