Acquisitions - Purchase Price Allocation (Details) - Acquisitions 2017 $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($)
Business Acquisition [Line Items]
Cash paid for acquisition of businesses	$ 87.1
Amounts due to sellers	0.5
Non-monetary consideration	8.1
Estimated purchase price	95.7
Assets acquired:
Property and equipment	10.7
Goodwill and identifiable intangible assets	85.0
Other current and long-term assets	7.6
Liabilities assumed:
Long-term liabilities and deferred tax liabilities	(7.7)
Estimated purchase price	$ 95.7