Summary of Significant Accounting Polices (Tables)

12 Months Ended

Dec. 31, 2012

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 Common Stock And 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,
	2012		2011		2010
Net income	$	103,034	$	102,757	$	80,039
Weighted average common shares outstanding	72,909		72,787		72,369
Dilutive effect of stock-based awards	544		438		438
Shares used in computing diluted earnings per share	73,453		73,225		72,807
Basic earnings per share	$	1.41	$	1.41	$	1.11
Diluted earnings per share	$	1.40	$	1.40	$	1.10

- Definition

Tabular disclosure of the useful life and salvage value of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software.

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