CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Cash flows from continuing operating activities
Net income	$ 22,754	$ 7,359
Adjustments to reconcile net income to net cash provided by continuing operating activities:
Net loss from discontinued operations	23	59
Deferred income taxes	14,648	2,541
Gains on property insurance recoveries associated with property, plant and equipment	(5,147)
Depreciation, depletion and amortization of property, plant and equipment	17,362	13,060
Other	323	1,369
Cash provided (used) by changes in assets and liabilities (net of effects of discontinued operations):
Accounts receivable	(6,236)	(13,696)
Inventories	2,963	6,015
Prepaid and accrued income taxes	5,601	(10,853)
Other supplies, prepaid items and other	8,723	5,646
Accounts payable	(104)	(5,393)
Customer deposits	(4,305)	(6,529)
Other current and noncurrent liabilities	648	615
Deferred gain on insurance recoveries	(1,383)	6,685
Net cash provided by continuing operating activities	55,870	6,878
Cash flows from continuing investing activities
Expenditures for property, plant and equipment	(92,943)	(82,608)
Proceeds from property insurance recovery associated with property, plant and equipment	5,147	14,022
Proceeds from sales of property and equipment	169	1,224
Purchase of short-term investments	(14,500)
Proceeds from noncurrent restricted cash and cash equivalents	97,984
Deposits of current and noncurrent restricted cash and cash equivalents	(165,106)	(749)
Proceeds from noncurrent restricted investments	209,990
Purchase of noncurrent restricted investments	(50,000)
Proceeds from sales of carbon credits	1,536
Payments on contractual obligations-carbon credits	(1,245)
Other assets	(903)	(812)
Net cash used by continuing investing activities	(9,871)	(68,923)
Cash flows from continuing financing activities
Proceeds from long-term debt, net of fees		39,825
Payments on long-term debt	(5,240)	(4,661)
Payments on short-term financing	(8,165)	(5,577)
Proceeds from exercise of stock options	507	304
Excess income tax benefit associated with stock-based compensation		110
Dividends paid on preferred stocks	(300)	(300)
Net cash provided (used) by continuing financing activities	(13,198)	29,701
Cash flows of discontinued operations:
Operating cash flows	(92)	(104)
Net increase (decrease) in cash and cash equivalents	32,709	(32,448)
Cash and cash equivalents at beginning of period	143,750	98,020
Cash and cash equivalents at end of period	$ 176,459	$ 65,572