Earnings Per Share - Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Net income attributable to shareholders of Criteo S.A.	$ 5,227	$ 18,778	$ 26,402	$ 48,721
Weighted average number of shares outstanding (in shares)	60,080,598	64,868,545	61,059,345	64,600,869
Dilutive effect of :
Restricted share awards (RSU's) (in shares)	811,136	907,412	440,835	987,586
Share options and (BSPCEs) (in shares)	128,291	261,324	133,865	290,756
Share warrants (in shares)	7,770	29,764	10,782	37,008
Weighted average number of shares outstanding used to determine diluted earnings per share (in shares)	61,027,795	66,067,045	61,644,827	65,916,219
Diluted earnings per share (in USD per share)	$ 0.09	$ 0.28	$ 0.43	$ 0.74