CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
CURRENT ASSETS
Cash and cash equivalents	$ 183,838	$ 190,186
Short-term investments	124,257	106,806
Accounts receivable, less allowances (2019 - $5,548; 2018 - $7,380)	292,935	297,051
Other accounts receivable, less allowances (2019 - $469; 2018 - $806)	18,122	19,146
Prepaid expenses	25,365	25,304
Prepaid and refundable income taxes	8,186	1,726
Other	5,285	9,007
TOTAL CURRENT ASSETS	657,988	649,226
PROPERTY, PLANT AND EQUIPMENT
Land and structures	339,298	339,640
Revenue equipment	902,289	858,251
Service, office, and other equipment	229,691	199,230
Software	146,789	138,517
Leasehold improvements	10,212	9,365
TOTAL PROPERTY, PLANT AND EQUIPMENT, GROSS	1,628,279	1,545,003
Less allowances for depreciation and amortization	948,205	913,815
PROPERTY, PLANT AND EQUIPMENT, net	680,074	631,188
GOODWILL	108,320	108,320
INTANGIBLE ASSETS, net	65,583	68,949
OPERATING RIGHT-OF-USE ASSETS	67,404
DEFERRED INCOME TAXES	6,128	7,468
OTHER LONG-TERM ASSETS	85,135	74,080
TOTAL ASSETS	1,670,632	1,539,231
CURRENT LIABILITIES
Accounts payable	160,054	143,785
Income taxes payable	198	1,688
Accrued expenses	234,863	243,111
Current portion of long-term debt	50,197	54,075
Current portion of operating lease liabilities	18,492
Current portion of pension and postretirement liabilities	1,921	8,659
TOTAL CURRENT LIABILITIES	465,725	451,318
LONG-TERM DEBT, less current portion	248,223	237,600
OPERATING LEASE LIABILITIES, less current portion	52,782
PENSION AND POSTRETIREMENT LIABILITIES, less current portion	32,059	31,504
OTHER LONG-TERM LIABILITIES	38,151	44,686
DEFERRED INCOME TAXES	70,066	56,441
STOCKHOLDERS' EQUITY
Common stock, $0.01 par value, authorized 70,000,000 shares; issued 2019: 28,801,025 shares, 2018: 28,684,779 shares	288	287
Additional paid-in capital	331,773	325,712
Retained earnings	540,778	501,389
Treasury stock, at cost, 2019: 3,299,669 shares; 2018: 3,097,634 shares	(101,583)	(95,468)
Accumulated other comprehensive loss	(7,630)	(14,238)
TOTAL STOCKHOLDERS' EQUITY	763,626	717,682
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 1,670,632	$ 1,539,231