Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net income/(loss)	$ (23,855)	$ 18,568
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Deferred income taxes	(78)	7,908
Provision for uncollectible revenue	731	(1,406)
Depreciation and amortization	54,794	57,638
Other post-employment benefits	(401)	(56,678)
Qualified pension	(1,082)	2,036
Stock-based compensation	1,634	2,666
Other non-cash items	1,285	1,102
Changes in assets and liabilities arising from operations:
Accounts receivable	902	(1,841)
Prepaid and other assets	2,005	(79)
Accounts payable and accrued liabilities	(1,032)	3,349
Accrued interest payable	(6,701)	(6,563)
Other assets and liabilities, net	33	(2,281)
Total adjustments	52,090	5,851
Net cash provided by operating activities	28,235	24,419
Cash flows from investing activities:
Net capital additions	(22,066)	(25,880)
Distributions from investments and proceeds from the sale of property and equipment	243	175
Net cash used in investing activities	(21,823)	(25,705)
Cash flows from financing activities:
Repayments of long-term debt	(1,600)	(1,600)
Proceeds from exercise of stock options	2	2
Repurchases of common stock to satisfy tax withholding obligations	(695)	(388)
Repayment of capital lease obligations	(296)	(224)
Net cash used in financing activities	(2,589)	(2,210)
Net change	3,823	(3,496)
Cash, beginning of period	34,924	26,560
Cash, end of period	38,747	23,064
Supplemental disclosure of cash flow information:
Capital additions included in accounts payable	6,520	8,691
Acquisition of property and equipment by capital lease	$ 57	$ 355