Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities:
Net income/(loss)	$ 47,883	$ (4,948)
Adjustments to reconcile net income/(loss) to net cash provided by operating activities:
Deferred income taxes	20,123	(678)
Provision for uncollectible revenue	(1,095)	4,065
Depreciation and amortization	112,743	111,124
Other post-employment benefits	(113,365)	(70,191)
Qualified pension	498	3,816
Stock-based compensation	3,917	4,109
Other non-cash items	2,509	2,066
Changes in assets and liabilities arising from operations:
Accounts receivable	(48)	1,605
Prepaid and other assets	(1,031)	4,089
Accounts payable and accrued liabilities	1,784	(24,480)
Accrued interest payable	0	(1)
Other assets and liabilities, net	(3,510)	(939)
Total adjustments	22,525	34,585
Net cash provided by operating activities	70,408	29,637
Cash flows from investing activities:
Net capital additions	(52,685)	(54,728)
Distributions from investments and proceeds from the sale of property and equipment	498	217
Net cash used in investing activities	(52,187)	(54,511)
Cash flows from financing activities:
Repayments of long-term debt	(3,200)	(3,200)
Restricted cash	(1)	0
Proceeds from exercise of stock options	9	13
Repayment of capital lease obligations	(473)	(378)
Net cash used in financing activities	(3,665)	(3,565)
Net change	14,556	(28,439)
Cash, beginning of period	26,560	37,587
Cash, end of period	41,116	9,148
Supplemental disclosure of cash flow information:
Capital additions included in accounts payable	9,904	10,683
Acquisition of property and equipment by capital lease	$ 713	$ 748