Variable Interest Entities (Details) - Variable Interest Entity, Primary Beneficiary - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Variable Interest Entity [Line Items]
Assets	$ 91.9		$ 91.9		$ 80.6
Liabilities	77.2		77.2		67.1
Revenues	82.4	$ 30.3	156.5	$ 30.3
Operating expenses
Variable Interest Entity [Line Items]
Expenses	79.1	$ 29.5	151.1	$ 29.5
Cash and Cash Equivalents
Variable Interest Entity [Line Items]
Assets	16.2		16.2		14.3
Accounts receivable, net of allowance
Variable Interest Entity [Line Items]
Assets	63.8		63.8		54.7
Other current assets
Variable Interest Entity [Line Items]
Assets	5.3		5.3		3.8
Property and equipment, net of accumulated depreciation
Variable Interest Entity [Line Items]
Assets	3.9		3.9		4.8
Other long-term assets
Variable Interest Entity [Line Items]
Assets	2.7		2.7		3.0
Accounts payable
Variable Interest Entity [Line Items]
Liabilities	46.2		46.2		44.9
Accrued expenses, other
Variable Interest Entity [Line Items]
Liabilities	12.4		12.4		8.1
Other current liabilities
Variable Interest Entity [Line Items]
Liabilities	9.5		9.5		8.9
Other long-term liabilities
Variable Interest Entity [Line Items]
Liabilities	$ 9.1		$ 9.1		$ 5.2