Acquisitions, Goodwill and Other Intangible Assets - Schedule of Recognized Identified Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Business Combination, Consideration Transferred [Abstract]
Cash, net of cash acquired	$ 21,840	$ 88,646
Identifiable assets acquired and liabilities assumed:
Goodwill	$ 1,504,341		$ 1,520,575
2021 Acquisitions
Business Combination, Consideration Transferred [Abstract]
Cash, net of cash acquired			1,289,100
Shares transferred			181,700
Estimated fair value of contingent consideration			100,000
Total consideration			1,570,500
Identifiable assets acquired and liabilities assumed:
Accounts receivable and contract assets			680,400
Current assets			42,300
Property and equipment			497,800
Long-term assets, primarily operating lease right-of-use assets			166,900
Amortizing intangible assets			608,800
Accounts payable			(157,300)
Current liabilities, including current portion of operating lease liabilities			(291,600)
Long-term debt, including finance lease obligations			(4,600)
Long-term liabilities, primarily operating lease liabilities and deferred income taxes			(226,500)
Total identifiable net assets			1,316,200
Goodwill			257,800
Total net assets acquired, including goodwill			1,574,000
Bargain purchase gain			(3,500)
2021 Acquisitions | Contingent Consideration
Business Combination, Consideration Transferred [Abstract]
Estimated fair value of contingent consideration			99,700
HMG
Business Combination, Consideration Transferred [Abstract]
Cash, net of cash acquired			416,900
Shares transferred			181,700
Total consideration			598,600
Identifiable assets acquired and liabilities assumed:
Accounts receivable and contract assets			409,800
Current assets			14,600
Property and equipment			247,000
Long-term assets, primarily operating lease right-of-use assets			85,100
Amortizing intangible assets			164,600
Accounts payable			(108,000)
Current liabilities, including current portion of operating lease liabilities			(155,300)
Long-term debt, including finance lease obligations			(200)
Long-term liabilities, primarily operating lease liabilities and deferred income taxes			(150,000)
Total identifiable net assets			507,600
Goodwill			91,000
Total net assets acquired, including goodwill			598,600
Bargain purchase gain			0
HMG | Contingent Consideration
Business Combination, Consideration Transferred [Abstract]
Estimated fair value of contingent consideration			0
All other
Business Combination, Consideration Transferred [Abstract]
Cash, net of cash acquired			872,200
Shares transferred			0
Total consideration			971,900
Identifiable assets acquired and liabilities assumed:
Accounts receivable and contract assets			270,600
Current assets			27,700
Property and equipment			250,800
Long-term assets, primarily operating lease right-of-use assets			81,800
Amortizing intangible assets			444,200
Accounts payable			(49,300)
Current liabilities, including current portion of operating lease liabilities			(136,300)
Long-term debt, including finance lease obligations			(4,400)
Long-term liabilities, primarily operating lease liabilities and deferred income taxes			(76,500)
Total identifiable net assets			808,600
Goodwill			166,800
Total net assets acquired, including goodwill			975,400
Bargain purchase gain			(3,500)
All other | Contingent Consideration
Business Combination, Consideration Transferred [Abstract]
Estimated fair value of contingent consideration			$ 99,700