CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
CURRENT ASSETS
Cash and cash equivalents	$ 102,569	$ 114,280
Short-term investments	54,148	56,838
Restricted cash		962
Accounts receivable, less allowances (2017 – $6,046; 2016 – $5,437)	282,856	260,643
Other accounts receivable, less allowances (2017 – $890; 2016 – $849)	19,052	22,041
Prepaid expenses	24,668	22,124
Prepaid and refundable income taxes	10,098	9,909
Other	8,293	4,300
TOTAL CURRENT ASSETS	501,684	491,097
PROPERTY, PLANT AND EQUIPMENT
Land and structures	338,228	324,086
Revenue equipment	763,567	743,860
Service, office, and other equipment	161,555	154,119
Software	124,135	120,877
Leasehold improvements	9,008	8,758
TOTAL PROPERTY, PLANT AND EQUIPMENT, GROSS	1,396,493	1,351,700
Less allowances for depreciation and amortization	841,245	819,174
PROPERTY, PLANT AND EQUIPMENT, net	555,248	532,526
GOODWILL	108,981	108,875
INTANGIBLE ASSETS, net	78,237	80,507
DEFERRED INCOME TAXES	2,722	2,978
OTHER LONG-TERM ASSETS	65,389	66,095
TOTAL ASSETS	1,312,261	1,282,078
CURRENT LIABILITIES
Accounts payable	142,373	133,301
Accrued expenses	200,052	198,731
Current portion of long-term debt	62,588	64,143
TOTAL CURRENT LIABILITIES	405,013	396,175
LONG-TERM DEBT, less current portion	194,730	179,530
PENSION AND POSTRETIREMENT LIABILITIES	37,028	35,848
OTHER LONG-TERM LIABILITIES	15,185	16,790
DEFERRED INCOME TAXES	58,225	54,680
STOCKHOLDERS' EQUITY
Common stock, $0.01 par value, authorized 70,000,000 shares; issued 2017: 28,450,025 shares; 2016: 28,174,424 shares	285	282
Additional paid-in capital	316,334	315,318
Retained earnings	391,143	386,917
Treasury stock, at cost, 2017: 2,759,919 shares; 2016: 2,565,399 shares	(83,656)	(80,045)
Accumulated other comprehensive loss	(22,026)	(23,417)
TOTAL STOCKHOLDERS' EQUITY	602,080	599,055
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 1,312,261	$ 1,282,078