Consolidated Statements of Cash Flow (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating activities
Net income	$ 24,595	$ 14,065	$ 14,053
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	37,365	37,818	35,530
Amortization	1,742	1,908	1,791
Gain on sale of assets	(1,802)	(783)	(437)
Deferred income taxes	(3,607)	3,428	3,384
Other	3,493	(1,501)	(1,895)
Changes in operating assets and liabilities:
Accounts receivable	(24,294)	(10,347)	(8,726)
Accounts payable and accrued expenses	(1,145)	6,152	5,229
Self-insurance accruals	4,468	2,855	717
Other assets, net	3,121	827	(371)
Adjustments to reconcile net income to net cash provided by operating activities	19,341	40,357	35,222
Net cash provided by operating activities	43,936	54,422	49,275
Capital expenditures:
Equipment	(29,294)	(34,370)	(34,237)
Land and buildings	(440)	(331)	(516)
Proceeds from sales of property and equipment	2,955	1,535	1,285
Purchases of businesses	(4,400)	(962)	(5,836)
Net cash used in investing activities	(31,179)	(34,128)	(39,304)
Financing activities
Revolving credit facility borrowings/(payments), net	4,200	(10,000)	(12,550)
Issuance of senior unsecured notes	0	0	30,000
Borrowings/(payments) of notes payable	1,155	(1,821)	(323)
Payments of long-term debt and capital leases	(649)	(955)	(1,569)
Purchase of common shares for treasury	(18,103)	(14,222)	(20,711)
Sale of common shares from treasury	10,735	7,316	7,214
Cash received on common-share subscriptions	1,841	0	26
Dividends	(2,556)	(2,362)	(2,436)
Net cash used in financing activities	(3,377)	(22,044)	(349)
Increase (Decrease) in cash and cash equivalents	9,380	(1,750)	9,622
Cash and cash equivalents, beginning of year	10,267	12,017	2,395
Cash and cash equivalents, end of year	$ 19,647	$ 10,267	$ 12,017