Acquisitions Of Businesses (Details) $ in Thousands		12 Months Ended
	Nov. 01, 2019 USD ($) Company	Dec. 31, 2021 USD ($) Company	Dec. 31, 2020 USD ($) Company	Dec. 31, 2019 USD ($) Company
Business Acquisition [Line Items]
Goodwill		$ 890,268	$ 851,783	$ 1,063,911
Amortization periods		7 years 6 months
Number of businesses acquired | Company	1	8	3	6
2021 Acquisitions
Business Acquisition [Line Items]
Purchase price		$ 131,200
Working capital acquired		22,900
Other net liabilities		600
Goodwill		38,300
Identifiable intangible assets		$ 70,600
2020 Acquisitions
Business Acquisition [Line Items]
Purchase price			$ 50,300
Working capital acquired			3,000
Other net liabilities			3,900
Goodwill			13,100
Identifiable intangible assets			$ 38,100
BKI [Member]
Business Acquisition [Line Items]
Business acquisition, percentage acquired	100.00%
Purchase price	$ 220,300
Working capital acquired	29,800
Other net assets	4,900
Goodwill	43,900
Identifiable intangible assets	$ 141,700
Amortization periods	10 years 6 months
2019 Acquisitions
Business Acquisition [Line Items]
Purchase price				$ 85,400
Working capital acquired				25,300
Other net assets				1,300
Goodwill				29,200
Identifiable intangible assets				$ 29,600