Balance Sheet Accounts - Schedule of Changes in Accumulated Other Comprehensive Loss by Components, Net of Income Taxes (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ (303.0)
Amortization of actuarial losses and prior service credits, net of $6.2 million of income taxes	9.7
Ending balance	(293.3)
Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Other comprehensive income, tax benefit	6.2
Actuarial Losses, Net
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(303.2)
Amortization of actuarial losses and prior service credits, net of $6.2 million of income taxes	9.8
Ending balance	(293.4)
Prior Service Credits, Net
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	0.2
Amortization of actuarial losses and prior service credits, net of $6.2 million of income taxes	(0.1)
Ending balance	$ 0.1