Shareholders' equity - Earnings Per Share (Basic and Diluted) (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Income from continuing operations	$ 447,962	$ 309,120	$ 229,606
(Loss) income from discontinued operations, net of tax	(232,916)	178,879	293,080
Net loss (income) attributable to noncontrolling interests from discontinued operations	58,698	(51,302)	(63,164)
Net income attributable to TEGNA Inc.	$ 273,744	$ 436,697	$ 459,522
Weighted average number of common shares outstanding - basic	215,587	216,358	224,688
Effect of dilutive securities
Weighted average number of common shares outstanding - diluted	217,478	219,681	229,721
Earnings from continuing operations per share - basic (in dollars per share)	$ 2.08	$ 1.43	$ 1.02
Earnings from discontinued operations per share - basic (in dollars per share)	(0.81)	0.59	1.02
Net income per share - basic (in dollars per share)	1.27	2.02	2.04
Earnings from continuing operations per share - diluted (in dollars per share)	2.06	1.41	1.00
Earnings from discontinued operations per share - diluted (in dollars per share)	(0.80)	0.58	1.00
Net income per share - diluted (in dollars per share)	$ 1.26	$ 1.99	$ 2.00
Restricted Stock
Effect of dilutive securities
Effect of dilutive securities (in shares)	659	1,424	2,236
Performance Shares
Effect of dilutive securities
Effect of dilutive securities (in shares)	550	997	1,867
Stock Options
Effect of dilutive securities
Effect of dilutive securities (in shares)	682	902	930