Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 14,612	$ 6,377
Trade accounts receivable, net	920,767	745,288
Other receivables, net	283,499	189,665
Inventories	20,688	18,577
Prepaid expenses	99,162	107,513
Total current assets	1,338,728	1,067,420
Property and equipment, at cost:
Revenue and service equipment	4,158,878	3,820,439
Land	47,231	46,827
Structures and improvements	202,730	175,900
Furniture and office equipment	261,625	215,749
Total property and equipment	4,670,464	4,258,915
Less accumulated depreciation	1,687,133	1,440,124
Net property and equipment	2,983,331	2,818,791
Goodwill	39,764
Other intangible assets, net	73,691	2,356
Other assets	29,835	62,160
Total assets	4,465,349	3,950,727
Current liabilities:
Trade accounts payable	598,594	384,308
Claims accruals	251,980	231,484
Accrued payroll	42,382	51,929
Other accrued expenses	28,888	27,152
Total current liabilities	921,844	694,873
Long-term debt	1,085,649	986,278
Other long-term liabilities	76,661	64,881
Deferred income taxes	541,870	790,634
Total liabilities	2,626,024	2,536,666
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, 2017 and 2016, of which 109,753,008 shares and 111,305,021 shares were outstanding at December 31, 2017 and 2016, respectively)	1,671	1,671
Additional paid-in capital	310,811	293,087
Retained earnings	3,803,844	3,218,943
Treasury stock, at cost (57,346,424 shares at December 31, 2017, and 55,794,411 shares at December 31, 2016)	(2,277,001)	(2,099,640)
Total stockholders’ equity	1,839,325	1,414,061
Total liabilities and stockholders' equity	$ 4,465,349	$ 3,950,727