Acquisitions - Intangible Assets Acquired (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2020	Jul. 10, 2017
Farner-Bocken Company
Business Acquisition [Line Items]
Other intangible assets	$ 22.6		$ 22.6
Customer relationships | Farner-Bocken Company
Business Acquisition [Line Items]
Other intangible assets	19.7
Non-competition agreements | Farner-Bocken Company
Business Acquisition [Line Items]
Other intangible assets	0.1
Trade names | Farner-Bocken Company
Business Acquisition [Line Items]
Other intangible assets	$ 2.8
Minimum | Customer relationships
Business Acquisition [Line Items]
Intangible assets, useful life		9 years
Minimum | Customer relationships | Farner-Bocken Company
Business Acquisition [Line Items]
Intangible assets, useful life	9 years
Minimum | Non-competition agreements
Business Acquisition [Line Items]
Intangible assets, useful life		1 year
Minimum | Non-competition agreements | Farner-Bocken Company
Business Acquisition [Line Items]
Intangible assets, useful life	4 years
Minimum | Trade names
Business Acquisition [Line Items]
Intangible assets, useful life	1 year	1 year
Maximum | Customer relationships
Business Acquisition [Line Items]
Intangible assets, useful life		15 years
Maximum | Customer relationships | Farner-Bocken Company
Business Acquisition [Line Items]
Intangible assets, useful life	11 years
Maximum | Non-competition agreements
Business Acquisition [Line Items]
Intangible assets, useful life		5 years
Maximum | Non-competition agreements | Farner-Bocken Company
Business Acquisition [Line Items]
Intangible assets, useful life	6 years
Maximum | Trade names
Business Acquisition [Line Items]
Intangible assets, useful life	2 years	2 years