Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 313,302	$ 35,000
Trade accounts receivable, net	1,124,403	1,011,829
Other receivables	185,849	230,331
Inventories	23,804	21,106
Prepaid expenses	194,759	183,033
Total current assets	1,842,117	1,481,299
Property and equipment, at cost:
Revenue and service equipment	4,991,662	4,837,747
Land	62,145	58,692
Structures and improvements	307,869	302,184
Software, office equipment and furniture	547,034	442,183
Total property and equipment	5,908,710	5,640,806
Less accumulated depreciation	2,219,816	2,019,940
Net property and equipment	3,688,894	3,620,866
Goodwill	105,367	96,326
Other intangible assets, net	106,755	106,506
Other assets	185,215	165,857
Total assets	5,928,348	5,470,854
Current liabilities:
Trade accounts payable	587,510	602,601
Claims accruals	276,056	279,590
Accrued payroll and payroll taxes	130,943	68,220
Other accrued expenses	90,294	85,355
Total current liabilities	1,084,803	1,035,766
Long-term debt	1,305,424	1,295,740
Other long-term liabilities	245,961	173,241
Deferred income taxes	692,022	699,078
Total liabilities	3,328,210	3,203,825
Commitments and contingencies (Note 10)
Stockholders’ equity:
Preferred stock, $100 par value. 10 million shares authorized; none outstanding	0	0
Common stock, $.01 par value. 1 billion shares authorized; (167,099,432 shares issued at December 31, 2020 and 2019, of which 105,653,644 and 106,212,908 shares were outstanding at December 31, 2020 and 2019, respectively)	1,671	1,671
Additional paid-in capital	408,244	374,049
Retained earnings	4,984,739	4,592,938
Treasury stock, at cost (61,445,788 shares at December 31, 2020, and 60,886,524 shares at December 31, 2019)	(2,794,516)	(2,701,629)
Total stockholders’ equity	2,600,138	2,267,029
Total liabilities and stockholders' equity	$ 5,928,348	$ 5,470,854