CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash Flows from Operating Activities
Net income	$ 29,586	$ 16,303	$ 12,993
Adjustments to reconcile net income to net cash provided by operating activities:
Impairments on assets held for sale	0	0	645
Goodwill impairment	0	10,952	0
Depreciation	56,583	57,961	45,350
Amortization	4,139	6,452	10,420
Provision for bad debt	2,019	2,870	3,243
Stock based compensation expense	1,938	1,842	1,718
Excess tax benefits on stock option exercises	(101)	(106)	(5)
Deferred income taxes	14,266	6,504	15,973
Net (gain) loss on disposal of equipment	753	426	(1,360)
Realized (gain) loss on disposal of investments	1	(66)	27
Unrealized (gains) losses on investments	(391)	(191)	132
Net (gain) loss from patronage and equity Investments	(837)	(894)	233
Write-off of unamortized loan fees	0	780	0
Other	2,272	1,526	257
(Increase) decrease in:
Accounts receivable	(2,594)	(8,246)	(1,891)
Materials and supplies	(927)	(2,321)	(1,080)
Income taxes receivable	(11,871)	7,790	(9,919)
Increase (decrease) in:
Accounts payable	(2,145)	(4,690)	(596)
Deferred lease payable	1,253	729	416
Other prepaids, deferrals and accruals	320	(647)	4,371
Net cash provided by operating activities	94,264	96,974	80,927
Cash Flows from Investing Activities
Acquisition of property, plant and equipment	(117,028)	(89,053)	(74,663)
Proceeds from sale of equipment	331	102	675
Proceeds from sales of assets	25	3,803	2,986
Purchase of investment securities	(12)	0	(84)
Proceeds from sale of investment securities	121	1,227	475
Net cash used in investing activities	(116,563)	(83,921)	(70,611)
Cash Flows From Financing Activities
Principal payments on long-term debt	(1,977)	(178,397)	(14,538)
Amounts borrowed under debt agreements	0	230,000	0
Cash paid for debt issuance costs	0	(2,418)	0
Dividends paid, net of dividends reinvested	(8,191)	(7,403)	(7,320)
Excess tax benefits on stock option exercises	101	106	5
Repurchases of stock	(1,600)	(143)	(92)
Proceeds from exercise of incentive stock options	1,196	414	50
Net cash provided by (used in) financing activities	(10,471)	42,159	(21,895)
Net increase (decrease) in cash and cash equivalents	(32,770)	55,212	(11,579)
Cash and cash equivalents:
Beginning	71,086	15,874	27,453
Ending	38,316	71,086	15,874
Cash payments for:
Interest, net of capitalized interest of $396 in 2013, $486 in 2012, and $215 in 2011	8,077	6,598	7,076
Income taxes paid (refunded), net	$ 17,483	$ (2,482)	$ 4,248