Merger with Deltic (Summary of Unaudited Pro Forma Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Business Combinations [Abstract]
Net sales	$ 289,199	$ 252,097	$ 795,992	$ 673,575
Net earnings attributable to PotlatchDeltic common shareholders	$ 61,327	$ 30,099	$ 142,314	$ 63,862
Basic earnings per share attributable to PotlatchDeltic common Shareholders	$ 0.91	$ 0.44	$ 2.13	$ 0.95
Diluted earnings per share attributable to PotlatchDeltic common shareholders	$ 0.91	$ 0.44	$ 2.12	$ 0.95