Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash	$ 10,301	$ 13,121
Accounts receivable, net	158,078	168,671
Operating supplies	13,706	10,069
Other current assets	15,153	17,264
Total current assets	197,238	209,125
Property and equipment	627,935	616,036
Less accumulated depreciation	427,632	422,853
Property and equipment, net	200,303	193,183
Other assets	35,284	29,156
Identified intangible assets and goodwill, net	41,375	41,671
Total assets	474,200	473,135
Current liabilities:
Accounts payable	39,597	45,093
Accrued expenses	32,312	42,816
Other current liabilities	37,001	40,748
Total current liabilities	108,910	128,657
Long-term debt	146,402	119,210
Self-insurance accruals	46,368	43,912
Other noncurrent liabilities	19,706	19,966
Total liabilities	321,386	311,745
Redeemable common shares related to 401KSOP and Employee Stock Ownership Plan (ESOP); 6,645 and 6,467 shares at redemption value as of March 31, 2018 and December 31, 2017	126,924	123,520
Common shareholders' equity:
Common shares, $1.00 par value, per share; 48,000 shares authorized; 36,269 and 36,447 shares issued and outstanding before deducting treasury shares and which excludes 6,645 and 6,467 shares subject to redemption as of March 31, 2018 and December 31, 2017	36,269	36,447
Additional paid-in capital	58,132	58,554
Common shares subscribed, unissued	7,457	7,529
Retained earnings	136,229	143,835
Accumulated other comprehensive loss	(9,079)	(8,393)
Shareholders' equity before treasury stock	229,008	237,972
Less: Cost of common shares held in treasury; 18,752 shares at March 31, 2018 and 18,693 shares at December 31, 2017	201,489	198,327
Common shares subscription receivable	1,629	1,775
Total common shareholders' equity	25,890	37,870
Total liabilities and shareholders' equity	$ 474,200	$ 473,135