Acquisitions (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired	$ 368.0
Business Combination, Contingent Consideration, Liability	6.0
Proceeds from revolving facility	75.0
Goodwill	883.0	$ 761.2	$ 716.8
Business Combination, Consideration Transferred			8.3
Indefinite-Lived Trade Name	59.0
Finite-Lived Customer Relationships, Gross	112.0
Other Finite-Lived Intangible Assets, Gross	33.0
Finite-Lived Intangible Asset, Acquired Backlog Revenue	6.0
Business Acquisition, Pro Forma Revenue	2,774.2	2,612.1
Business Acquisition, Pro Forma Net Income (Loss)	$ 446.8	$ 256.9
Business Acquisition, Pro Forma Earnings Per Share, Basic	$ 4.70	$ 2.70
Business Acquisition, Pro Forma Earnings Per Share, Diluted	$ 4.67	$ 2.68
Business Acquisition, Pro Forma Information, Amortization of Intangible Assets	9.7
Business Acquisition, Pro Forma Information, Amortization of Backlog Revenue	$ 3.9
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual	160.2
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual	(3.2)
Business Acquisition, Transaction Costs	10.0	$ 4.7
Payments to Acquire Interest in Subsidiaries and Affiliates	8.0		$ 3.3
2018 acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	28.9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory	28.5
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets	1.3
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	27.6
Goodwill	141.8
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	204.3
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets	0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable	(11.1)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other	(35.7)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities	(11.1)
Business Combination, Consideration Transferred	$ 374.5