Merger with Deltic (Summary of Unaudited Pro Forma Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Business Combinations [Abstract]
Net sales	$ 1,013,242	$ 920,860
Net earnings attributable to PotlatchDeltic common shareholders	$ 145,685	$ 77,732
Basic earnings per share attributable to PotlatchDeltic common shareholders	$ 2.16	$ 1.15
Diluted earnings per share attributable to PotlatchDeltic common shareholders	$ 2.15	$ 1.15