Supplemental equity information - Loss Per Share (Basic and Diluted) (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 29, 2019	Sep. 30, 2020	Sep. 29, 2019
Equity [Abstract]
Net loss attributable to Gannett	$ (31,260)	$ (18,463)	$ (548,305)	$ (24,754)
Basic weighted average shares outstanding (in shares)	132,223	60,034	131,425	60,010
Diluted weighted average shares outstanding (in shares)	132,223	60,034	131,425	60,010