Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Apr. 04, 2015	Dec. 31, 2014
Current assets:
Cash	$ 16,696	$ 18,415
Accounts receivable, net	106,474	111,598
Operating supplies	7,254	6,968
Other current assets	26,749	30,215
Total current assets	157,173	167,196
Property and equipment	547,224	532,949
Less accumulated depreciation	377,958	372,066
Property and equipment, net	169,266	160,883
Other assets	20,882	18,862
Identified intangible assets and goodwill, net	33,528	34,063
Total assets	380,849	381,004
Current liabilities:
Accounts payable	37,041	42,140
Accrued expenses	23,535	34,925
Other current liabilities	28,346	31,288
Total current liabilities	88,922	108,353
Long-term debt	103,307	81,306
Self-insurance accruals	37,568	35,886
Other noncurrent liabilities	19,077	18,968
Total liabilities	248,874	244,513
Common shareholders' equity:
Common shares, $1.00 par value, per share; 24,000 shares authorized; 21,457 shares issued and outstanding before treasury shares as of April 4, 2015	21,457	21,457
Additional paid-in capital	11,822	9,461
Common shares subscribed, unissued	9,343	9,381
Retained earnings	247,258	251,470
Accumulated other comprehensive loss	(13,464)	(11,523)
Shareholders' equity before treasury stock	276,416	280,246
Less: Cost of Common shares held in treasury; 8,243 shares at April 4, 2015 and 8,292 shares at December 31, 2014	139,015	138,155
Common shares subscription receivable	5,426	5,600
Common shareholders' equity	131,975	136,491
Total liabilities and shareholders' equity	$ 380,849	$ 381,004