Shareholders' equity - Earnings Per Share (Basic and Diluted) (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Income from continuing operations	$ 286,235	$ 401,340	$ 447,962
Income (loss) from discontinued operations, net of tax	0	4,325	(232,916)
Net loss attributable to noncontrolling interests from discontinued operations	0	0	58,698
Net income attributable to TEGNA Inc.	$ 286,235	$ 405,665	$ 273,744
Weighted average number of common shares outstanding - basic	217,138	216,184	215,587
Effect of dilutive securities
Weighted average number of common shares outstanding - diluted	217,977	216,621	217,478
Earnings from continuing operations per share - basic (in dollars per share)	$ 1.32	$ 1.86	$ 2.08
Earnings from discontinued operations per share - basic (in dollars per share)	0	0.02	(0.81)
Net income per share - basic (in dollars per share)	1.32	1.88	1.27
Earnings from continuing operations per share - diluted (in dollars per share)	1.31	1.85	2.06
Earnings from discontinued operations per share - diluted (in dollars per share)	0	0.02	(0.80)
Net income per share - diluted (in dollars per share)	$ 1.31	$ 1.87	$ 1.26
Restricted Stock
Effect of dilutive securities
Effect of dilutive securities (in shares)	461	139	659
Performance Shares
Effect of dilutive securities
Effect of dilutive securities (in shares)	346	97	550
Stock Options
Effect of dilutive securities
Effect of dilutive securities (in shares)	32	201	682