Consolidated Condensed Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 10,398	$ 15,791
Receivables:
Trade, net	82,090	74,886
Other	7,037	6,131
Prepaid expenses and other	19,186	19,810
Total current assets	118,711	116,618
Property and equipment:
Revenue equipment, buildings and land, office equipment and other	808,750	783,648
Accumulated depreciation	(217,558)	(211,728)
Net property and equipment	591,192	571,920
Other assets	2,062	1,865
Total assets	711,965	690,403
Current liabilities:
Accounts payable and accrued liabilities	49,421	38,100
Insurance and claims accruals	25,414	26,177
Total current liabilities	74,835	64,277
Deferred income taxes	101,676	100,626
Total liabilities	176,511	164,903
Stockholders’ equity:
Preferred stock, $.01 par value per share; 2,000,000 shares authorized; no shares issued and outstanding
Common stock, $.01 par value per share; 96,000,000 shares authorized; 54,589,542 shares at March 31, 2018, and 54,533,455 shares at December 31, 2017, issued and outstanding	546	545
Additional paid-in capital	76,915	76,413
Retained earnings	457,993	448,542
Total stockholders’ equity	535,454	525,500
Total liabilities and stockholders’ equity	$ 711,965	$ 690,403

Sum of the carrying values as of the balance sheet date of obligations incurred through that date and due within one year (or the operating cycle, if longer), including liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received, taxes, interest, rent and utilities, accrued salaries and bonuses, payroll taxes and fringe benefits.

Name:	us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682