CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Cash flows from operating activities
Net income (loss)	$ (48,704)	$ 73,295
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and depletion	51,742	81,944
Amortization of port access contract rights	2,783	0
Accretion	9,960	12,066
Goodwill impairment	33,355	0
Loss (income) from unconsolidated affiliates, net of tax	(294)	(562)
Distributions of income from unconsolidated affiliates	0	1,250
Deferred income taxes	(10,115)	30,715
Gain on sale of Decker Mine interest	0	(74,262)
Tax agreement benefit	0	(58,595)
Equity-based compensation expense	4,819	5,819
Derivative mark-to-market (gains) losses	17,781	(16,052)
Cash received (paid) for derivative financial instruments	(1,618)	16,905
Premium payments on derivative financial instruments	(5,813)	0
Non-cash interest expense related to early retirement of debt and refinancings	0	7,338
Net periodic postretirement benefit cost	6,072	5,247
Other	1,953	4,021
Changes in operating assets and liabilities:
Accounts receivable	25,614	(6,459)
Inventories, net	4,300	(3,927)
Due to or from related parties	(3,925)	137
Other assets	(10,875)	4,173
Accounts payable and accrued expenses	(14,191)	4,850
Tax agreement liability	0	(45,000)
Asset retirement obligations	(780)	(788)
Net cash provided by (used in) operating activities	62,064	42,115
Investing activities
Purchases of property, plant and equipment	(28,125)	(14,680)
Cash paid for capitalized interest	(404)	(4,066)
Investments in marketable securities	0	(8,159)
Maturity and redemption of investments	0	88,845
Investment in port access contract rights	0	(37,100)
Investment in development projects	(1,526)	(3,522)
Investment in unconsolidated affiliates	(5,383)	0
Payment of restricted cash	(6,500)	0
Other	185	(1,830)
Net cash provided by (used in) investing activities	(41,753)	19,488
Financing activities
Principal payments on federal coal leases	(63,970)	(58,958)
Issuance of senior notes	0	200,000
Repayment of senior notes	0	(300,000)
Payment of deferred financing costs	(342)	(14,683)
Other	(1,225)	(305)
Net cash provided by (used in) financing activities	(65,537)	(173,946)
Net increase (decrease) in cash and cash equivalents	(45,226)	(112,343)
Cash and cash equivalents at beginning of period	168,745	231,633
Cash and cash equivalents at end of period	123,519	119,290
Supplemental cash flow disclosures
Interest paid	32,827	37,017
Income taxes paid (refunded)	10,123	(5,798)
Supplemental noncash investing and financing activities
Capital expenditures included in accounts payable	6,401	1,816
Assets acquired under capital leases	0	1,209
Port access contract rights acquired in sale of Decker Mine interest	$ 0	$ 5,000