CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
CURRENT ASSETS
Cash and cash equivalents	$ 95,728	$ 105,354
Short-term investments	35,960	35,906
Restricted cash, cash equivalents, and short-term investments	1,903	1,902
Accounts receivable, less allowances (2014 - $4,516; 2013 - $4,533)	221,870	202,540
Other accounts receivable, less allowances (2014 - $1,441; 2013 - $1,422)	6,940	7,272
Prepaid expenses	22,178	19,016
Deferred income taxes	36,018	37,482
Prepaid and refundable income taxes	4,205	2,061
Other	8,144	6,952
TOTAL CURRENT ASSETS	432,946	418,485
PROPERTY, PLANT AND EQUIPMENT
Land and structures	248,310	245,805
Revenue equipment	588,935	589,902
Service, office, and other equipment	124,273	124,303
Software	112,896	110,998
Leasehold improvements	23,637	23,582
TOTAL PROPERTY, PLANT AND EQUIPMENT, GROSS	1,098,051	1,094,590
Less allowances for depreciation and amortization	713,493	700,193
PROPERTY, PLANT AND EQUIPMENT, net	384,558	394,397
GOODWILL	76,448	76,448
INTANGIBLE ASSETS, net	74,344	75,387
OTHER ASSETS	53,349	52,609
TOTAL ASSETS	1,021,645	1,017,326
CURRENT LIABILITIES
Bank overdraft and drafts payable	15,009	13,609
Accounts payable	110,364	89,091
Income taxes payable	162	1,782
Accrued expenses	171,433	173,622
Current portion of long-term debt	30,725	31,513
TOTAL CURRENT LIABILITIES	327,693	309,617
LONG-TERM DEBT, less current portion	74,355	81,332
PENSION AND POSTRETIREMENT LIABILITIES	34,587	26,847
OTHER LIABILITIES	13,217	15,041
DEFERRED INCOME TAXES	57,596	64,028
STOCKHOLDERS' EQUITY
Common stock, $0.01 par value, authorized 70,000,000 shares; issued 2014: 27,547,487 shares; 2013: 27,507,241 shares	275	275
Additional paid-in capital	298,635	296,133
Retained earnings	290,723	296,735
Treasury stock, at cost, 1,677,932 shares	(57,770)	(57,770)
Accumulated other comprehensive loss	(17,666)	(14,912)
TOTAL STOCKHOLDERS' EQUITY	514,197	520,461
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 1,021,645	$ 1,017,326