Business Acquisitions - Narrative (Details) - USD ($)	3 Months Ended		12 Months Ended
	Sep. 30, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Acquisition of businesses, net of cash acquired			$ 173,400,000	$ 163,400,000	$ 183,800,000
Goodwill			$ 991,000,000	$ 928,500,000	$ 874,700,000
R.W. Lyall & Company, Inc. [Member]
Business Acquisition [Line Items]
Acquisition of businesses, net of cash acquired		$ 129,100,000
Intangible assets acquired		68,900,000
Goodwill		$ 48,700,000
Intangible assets, weighted average useful life		21 years
Elmot Reality Associates, LLC, Elmot Reality Associates II, LLC, and DelRi LLC [Member]
Business Acquisition [Line Items]
Acquisition of businesses, net of cash acquired		$ 40,300,000
Intangible assets acquired		16,900,000
Goodwill		$ 18,100,000
Intangible assets, weighted average useful life		19 years
Goodwill, expected to be tax deductible		$ 0
Jiangsu Xiangyuan Electrical Equipment Co., Ltd. (Longbow) [Member]
Business Acquisition [Line Items]
Acquisition of businesses, net of cash acquired	$ 14,500,000
Intangible assets acquired	6,900,000
Goodwill	2,500,000
Cash received	2,000,000
Payments to acquire business at closing	2,900,000
Future installment payments	$ 11,600,000
Intangible assets, useful life	11 years