Business Acquisitions - Allocation of Aggregate Purchase Consideration (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Oct. 28, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Goodwill	$ 1,867,430		$ 1,633,033	$ 1,380,376
Deferred revenue	(22,400)		(28,000)
Fiscal 2020 Acquisitions
Business Acquisition [Line Items]
Accounts receivable	46,332
Prepaid expenses and other current assets	9,105
Property and equipment	2,248
Operating lease right of use asset	10,644
Goodwill	218,745
Other long-term assets	685
Deferred tax asset	992
Accounts payables and accrued expenses	(29,073)
Deferred revenue	(22,436)
Operating lease liabilities, current	(4,520)
Long-term debt	(910)
Operating lease liabilities, noncurrent	(13,104)
Income taxes payable	(3,297)
Liability for uncertain tax positions	(1,576)
Deferred tax liability	(53,870)
Other long-term liabilities	(9,269)
Total	497,750
Fiscal 2020 Acquisitions | Trade names
Business Acquisition [Line Items]
Finite-lived intangibles	67,670
Fiscal 2020 Acquisitions | Customer relationships
Business Acquisition [Line Items]
Finite-lived intangibles	222,582
Fiscal 2020 Acquisitions | Other intangibles
Business Acquisition [Line Items]
Finite-lived intangibles	$ 56,802
RetailMeNot, Inc.
Business Acquisition [Line Items]
Accounts receivable		$ 40,525
Prepaid expenses and other current assets		7,367
Property and equipment		587
Operating lease right of use asset		10,313
Goodwill		169,581
Other long-term assets		494
Deferred tax asset		605
Accounts payables and accrued expenses		(24,526)
Deferred revenue		(11,175)
Operating lease liabilities, current		(4,029)
Operating lease liabilities, noncurrent		(13,085)
Income taxes payable		(3,308)
Liability for uncertain tax positions		(1,576)
Deferred tax liability		(52,504)
Other long-term liabilities		(9,275)
Total		414,384
RetailMeNot, Inc. | Trade names
Business Acquisition [Line Items]
Finite-lived intangibles		62,940
RetailMeNot, Inc. | Customer relationships
Business Acquisition [Line Items]
Finite-lived intangibles		198,840
RetailMeNot, Inc. | Other intangibles
Business Acquisition [Line Items]
Finite-lived intangibles		$ 42,610
Fiscal 2019 Acquisitions
Business Acquisition [Line Items]
Accounts receivable			22,796
Prepaid expenses and other current assets			4,528
Property and equipment			4,625
Operating lease right of use asset			4,982
Goodwill			253,096
Other long-term assets			660
Accounts payables and accrued expenses			(31,292)
Other current liabilities			(516)
Deferred revenue			(27,953)
Operating lease liabilities, current			(1,768)
Operating lease liabilities, noncurrent			(3,215)
Income taxes payable			(762)
Liability for uncertain tax positions			(170)
Deferred tax liability			(10,229)
Other long-term liabilities			(635)
Total			429,517
Fiscal 2019 Acquisitions | Trade names
Business Acquisition [Line Items]
Finite-lived intangibles			10,773
Fiscal 2019 Acquisitions | Customer relationships
Business Acquisition [Line Items]
Finite-lived intangibles			123,611
Fiscal 2019 Acquisitions | Trademarks
Business Acquisition [Line Items]
Finite-lived intangibles			32,540
Fiscal 2019 Acquisitions | Other intangibles
Business Acquisition [Line Items]
Finite-lived intangibles			$ 48,446
Fiscal 2018 Acquisitions
Business Acquisition [Line Items]
Cash				15,532
Accounts receivable				11,321
Prepaid expenses and other current assets				3,480
Property and equipment				4,755
Goodwill				194,282
Other long-term assets				341
Deferred tax asset				821
Accounts payables and accrued expenses				(10,864)
Deferred revenue				(37,113)
Finance lease				(956)
Income taxes payable				(1,458)
Deferred tax liability				(22,990)
Other long-term liabilities				(5,410)
Total				340,199
Fiscal 2018 Acquisitions | Trade names
Business Acquisition [Line Items]
Finite-lived intangibles				33,750
Fiscal 2018 Acquisitions | Customer relationships
Business Acquisition [Line Items]
Finite-lived intangibles				66,516
Fiscal 2018 Acquisitions | Trademarks
Business Acquisition [Line Items]
Finite-lived intangibles				3,285
Fiscal 2018 Acquisitions | Other intangibles
Business Acquisition [Line Items]
Finite-lived intangibles				$ 84,907