Summary of Significant Accounting Polices (Tables)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Schedule of Estimated Useful Life

For financial reporting purposes, assets are generally depreciated using the following estimated useful lives and salvage values:

	Lives	Salvage Values
Building and improvements	30 years	0%
Tractors	80 months	0%
Trailers	12 years	$1,000
Service and other equipment	3-10 years	0%

Schedule Of Basic and Diluted Earnings Per Share

The computation of basic and diluted earnings per share is shown below (in thousands, except per share amounts).

	Years Ended December 31,
	2019		2018		2017
Net income	$	166,944	$	168,148	$	202,889
Weighted average common shares outstanding	69,567		71,694		72,270
Dilutive effect of stock-based awards	459		363		288
Shares used in computing diluted earnings per share	70,026		72,057		72,558
Basic earnings per share	$	2.40	$	2.35	$	2.81
Diluted earnings per share	$	2.38	$	2.33	$	2.80