Summary of Significant Accounting Polices (Tables)

12 Months Ended

Dec. 31, 2018

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,
	2018		2017		2016
Net income	$	168,148	$	202,889	$	79,129
Weighted average common shares outstanding	71,694		72,270		72,057
Dilutive effect of stock-based awards	363		288		336
Shares used in computing diluted earnings per share	72,057		72,558		72,393
Basic earnings per share	$	2.35	$	2.81	$	1.10
Diluted earnings per share	$	2.33	$	2.80	$	1.09