Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net income	$ 1,432	$ 4,604
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	43,221	37,604
Employee retirement benefits	(3,565)	(6,494)
Provision for uncollectibles	1,634	1,478
Stock based compensation	900	2,099
Deferred income taxes	1,621	3,544
Changes in operating assets and liabilities:
Receivables	(3,025)	979
Material and supplies	(92)	121
Prepaid expenses and other current assets	(1,944)	(2,090)
Accounts payable and accrued expenses	(2,037)	(3,896)
Advance billings and customer deposits	668	(181)
Other current liabilities	(465)	113
Other	1,445	758
Net cash provided by operating activities	39,793	38,639
Cash flows from investing activities:
Capital expenditures	(52,916)	(51,315)
Funds released from restricted cash account	400
Net cash used in investing activities	(52,516)	(51,315)
Cash flows from financing activities:
Proceeds from stock issuance	3,341
Proceeds from installment financing	2,279	2,085
Repayment of capital lease and installment financing	(1,976)	(856)
Repayment of debt	(1,500)	(1,500)
Refinancing costs	(150)
Taxes paid related to net share settlement of equity awards	(928)	(1,005)
Net cash provided by (used in) financing activities	1,066	(1,276)
Net change in cash and cash equivalents	(11,657)	(13,952)
Cash and cash equivalents, beginning of period	39,885	49,551
Cash and cash equivalents, end of period	28,228	35,599
Supplemental disclosure of cash flow information:
Interest paid, net of amounts capitalized	$ 7,604	$ 7,433