Business Acquisitions - Supplementary Information on Unaudited Pro Forma Financial Basis (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
RetailMeNot, Inc.
Revenues	$ 1,639,495	$ 1,589,437
Net income	$ 140,880	$ 190,709
EPS - Basic (in usd per share)	$ 3.03	$ 3.94
EPS - Diluted (in usd per share)	$ 2.98	$ 3.83
Fiscal 2020 Acquisitions
Revenues	$ 1,671,955	$ 1,633,861
Net income	$ 140,534	$ 178,654
EPS - Basic (in usd per share)	$ 3.02	$ 3.69
EPS - Diluted (in usd per share)	$ 2.97	$ 3.59
Fiscal 2019 Acquisitions
Revenues		$ 1,474,132	$ 1,427,914
Net income		$ 211,303	$ 104,710
EPS - Basic (in usd per share)		$ 4.36	$ 2.15
EPS - Diluted (in usd per share)		$ 4.24	$ 2.11
Fiscal 2018 Acquisitions
Revenues			$ 1,264,544	$ 1,218,530
Net income			$ 121,727	$ 123,378
EPS - Basic (in usd per share)			$ 2.50	$ 2.56
EPS - Diluted (in usd per share)			$ 2.45	$ 2.50