Acquisitions and Dispositions - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Aug. 02, 2021	Dec. 31, 2020	Oct. 30, 2020	Aug. 14, 2020	Feb. 14, 2020	Dec. 31, 2019
Business Acquisition [Line Items]
Goodwill	$ 1,652,723		$ 351,725				$ 325,185
2020 Acquisitions
Business Acquisition [Line Items]
Cash, cash equivalents and restricted cash			139
Accounts receivable and other current assets			8,458
Fixed Assets			180
Right-of-use lease assets - operating leases			734
Intangible assets			17,330
Other assets			182
Advance billings			(869)
Accounts payable and other current liabilities			(2,084)
Long-term portion of lease liabilities			(734)
Goodwill			23,782
Purchase price consideration			$ 47,118
MDC
Business Acquisition [Line Items]
Cash and cash equivalents		$ 130,153
Accounts receivable		413,839
Other current assets		41,736
Fixed Assets		80,047
Right-of-use lease assets - operating leases		253,629
Intangible assets		810,900
Other assets		16,818
Accounts payable		(170,361)
Accruals and other liabilities		(309,081)
Advance billings		(211,403)
Current portion of lease liabilities		(48,517)
Current portion of deferred acquisition consideration		(53,054)
Long-term debt		(901,736)
Revolving credit facility		(109,954)
Long-term portion of deferred acquisition consideration		(8,056)
Long-term portion of lease liabilities		(289,128)
Other liabilities		(132,394)
Redeemable noncontrolling interests		(25,990)
Preferred shares		(209,980)
Noncontrolling interests		(151,090)
Net liabilities assumed		(873,622)
Goodwill		1,299,374
Purchase price consideration		$ 425,752
Sloane and Company LLC
Business Acquisition [Line Items]
Cash, cash equivalents and restricted cash						$ 0
Accounts receivable and other current assets						2,768
Fixed Assets						72
Right-of-use lease assets - operating leases						0
Intangible assets						5,900
Other assets						0
Advance billings						(130)
Accounts payable and other current liabilities						(469)
Long-term portion of lease liabilities						0
Goodwill						16,275
Purchase price consideration						$ 24,416
Kettle
Business Acquisition [Line Items]
Cash, cash equivalents and restricted cash					$ 49
Accounts receivable and other current assets					2,732
Fixed Assets					58
Right-of-use lease assets - operating leases					533
Intangible assets					1,930
Other assets					172
Advance billings					(310)
Accounts payable and other current liabilities					(552)
Long-term portion of lease liabilities					(533)
Goodwill					1,323
Purchase price consideration					$ 5,402
Truelogic
Business Acquisition [Line Items]
Cash, cash equivalents and restricted cash				$ 90
Accounts receivable and other current assets				2,958
Fixed Assets				50
Right-of-use lease assets - operating leases				201
Intangible assets				9,500
Other assets				10
Advance billings				(429)
Accounts payable and other current liabilities				(1,063)
Long-term portion of lease liabilities				(201)
Goodwill				6,184
Purchase price consideration				$ 17,300
Goodstuff
Business Acquisition [Line Items]
Cash and cash equivalents	30,985
Accounts receivable	28,685
Other current assets	3,207
Fixed Assets	237
Right-of-use lease assets - operating leases	2,060
Intangible assets	14,974
Other assets	55
Accounts payable	(6,344)
Accruals and other liabilities	(27,353)
Advance billings	(15,956)
Current portion of lease liabilities	(857)
Income taxes payable	(967)
Long-term portion of lease liabilities	(3,744)
Other liabilities	(1,204)
Net liabilities assumed	23,778
Goodwill	4,275
Purchase price consideration	$ 28,053