CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
CURRENT ASSETS
Cash and cash equivalents	$ 109,034	$ 114,280
Short-term investments	57,052	56,838
Restricted cash		962
Accounts receivable, less allowances (2017 - $6,313; 2016 - $5,437)	301,941	260,643
Other accounts receivable, less allowances (2017 - $906; 2016 - $849)	15,337	22,041
Prepaid expenses	22,156	22,124
Prepaid and refundable income taxes	4,673	9,909
Other	8,834	4,300
TOTAL CURRENT ASSETS	519,027	491,097
PROPERTY, PLANT AND EQUIPMENT
Land and structures	340,889	324,086
Revenue equipment	773,859	743,860
Service, office, and other equipment	168,627	154,119
Software	127,109	120,877
Leasehold improvements	9,228	8,758
TOTAL PROPERTY, PLANT AND EQUIPMENT, GROSS	1,419,712	1,351,700
Less allowances for depreciation and amortization	850,054	819,174
PROPERTY, PLANT AND EQUIPMENT, net	569,658	532,526
GOODWILL	108,981	108,875
INTANGIBLE ASSETS, net	77,103	80,507
DEFERRED INCOME TAXES	2,747	2,978
OTHER LONG-TERM ASSETS	66,916	66,095
TOTAL ASSETS	1,344,432	1,282,078
CURRENT LIABILITIES
Accounts payable	147,889	133,301
Income taxes payable	167
Accrued expenses	202,408	198,731
Current portion of long-term debt	62,837	64,143
TOTAL CURRENT LIABILITIES	413,301	396,175
LONG-TERM DEBT, less current portion	200,181	179,530
PENSION AND POSTRETIREMENT LIABILITIES	40,168	35,848
OTHER LONG-TERM LIABILITIES	16,585	16,790
DEFERRED INCOME TAXES	60,632	54,680
STOCKHOLDERS' EQUITY
Common stock, $0.01 par value, authorized 70,000,000 shares; issued 2017: 28,478,150 shares; 2016: 28,174,424 shares	285	282
Additional paid-in capital	317,677	315,318
Retained earnings	403,868	386,917
Treasury stock, at cost, 2017: 2,851,578 shares; 2016: 2,565,399 shares	(86,064)	(80,045)
Accumulated other comprehensive loss	(22,201)	(23,417)
TOTAL STOCKHOLDERS' EQUITY	613,565	599,055
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 1,344,432	$ 1,282,078