CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
CURRENT ASSETS
Cash and cash equivalents	$ 191,646	$ 157,042
Short-term investments	69,567	45,909
Restricted cash	1,387	1,386
Accounts receivable, less allowances (2015 – $5,311; 2014 – $5,731)	242,656	228,056
Other accounts receivable, less allowances (2015 – $979; 2014 – $1,701)	7,119	6,582
Prepaid expenses	18,557	20,906
Deferred income taxes	41,349	40,220
Prepaid and refundable income taxes	3,057	9,920
Other	5,144	4,968
TOTAL CURRENT ASSETS	580,482	514,989
PROPERTY, PLANT AND EQUIPMENT
Land and structures	269,317	251,836
Revenue equipment	689,786	633,455
Service, office, and other equipment	142,536	136,145
Software	122,874	116,112
Leasehold improvements	24,962	24,377
TOTAL PROPERTY, PLANT AND EQUIPMENT, GROSS	1,249,475	1,161,925
Less allowances for depreciation and amortization	790,536	752,075
PROPERTY, PLANT AND EQUIPMENT, net	458,939	409,850
GOODWILL	81,278	77,078
INTANGIBLE ASSETS, net	70,410	72,809
OTHER ASSETS	53,177	52,896
TOTAL ASSETS	1,244,286	1,127,622
CURRENT LIABILITIES
Accounts payable	144,401	120,325
Income taxes payable	8,489	527
Accrued expenses	193,997	194,674
Current portion of long-term debt	35,050	25,256
TOTAL CURRENT LIABILITIES	381,937	340,782
LONG-TERM DEBT, less current portion	156,553	102,474
PENSION AND POSTRETIREMENT LIABILITIES	49,978	42,418
OTHER LIABILITIES	12,755	16,667
DEFERRED INCOME TAXES	56,268	64,398
STOCKHOLDERS' EQUITY
Common stock, $0.01 par value, authorized 70,000,000 shares; issued 2015: 27,932,109 shares; 2014: 27,722,010 shares	279	277
Additional paid-in capital	307,939	303,045
Retained earnings	373,936	338,810
Treasury stock, at cost, 2015: 1,970,118 shares; 2014: 1,677,932 shares	(67,774)	(57,770)
Accumulated other comprehensive loss	(27,585)	(23,479)
TOTAL STOCKHOLDERS' EQUITY	586,795	560,883
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 1,244,286	$ 1,127,622