SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule Of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Net income attributable to Werner	$ 241,256	$ 259,052	$ 169,078
Weighted average common shares outstanding (in shares)	64,125	67,434	69,018
Dilutive effect of stock-based awards (in shares)	454	421	409
Shares used in computing diluted earnings per share (in shares)	64,579	67,855	69,427
Basic earnings per share (in dollars per share)	$ 3.76	$ 3.84	$ 2.45
Diluted earnings per share (in dollars per share)	$ 3.74	$ 3.82	$ 2.44