Acquisitions Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) business	Dec. 31, 2015 USD ($) business	Dec. 31, 2014 USD ($) business
Business Acquisition [Line Items]
Payments to acquire businesses, net of cash acquired	$ 190.1	$ 37.1	$ 289.0
Goodwill	$ 113.2	$ 21.2
Acquisitions, 2016 [Member]
Business Acquisition [Line Items]
Number of businesses acquired | business	3
Payments to acquire businesses, net of cash acquired	$ 190.0
Revenue of prior fiscal year	47.0
Goodwill	$ 113.0
Acquisitions, 2015 [Member]
Business Acquisition [Line Items]
Number of businesses acquired | business		2
Payments to acquire businesses, net of cash acquired		$ 37.0
Revenue of prior fiscal year		18.0
Goodwill		$ 21.0
Acquisitions, 2014 [Member]
Business Acquisition [Line Items]
Number of businesses acquired | business			6
Payments to acquire businesses, net of cash acquired			$ 289.0
Revenue of prior fiscal year			133.0
Goodwill			$ 151.0