CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
CASH PROVIDED BY OPERATIONS:
Net income	$ 150,978	$ 98,952
Adjustments to reconcile net income to net cash provided by operations:
Depreciation and amortization	131,147	120,296
Deferred income taxes	(1,037)	4,793
Provision for pension and postretirement benefits	14,746	16,457
Share-based compensation expense	16,870	11,767
Gain on disposals of property, plant and equipment	(18,914)	(2,119)
Postretirement benefit claims paid	(1,995)	(2,069)
Contributions to pension plans	(6,223)	(32,099)
Asset impairment charges	0	2,896
Changes in current assets and liabilities:
Receivables - trade and other	(21,575)	(42,504)
Prepaid expenses and other current assets	(11,668)	(18,058)
Accounts payable	(40)	(14,543)
Accrued income taxes	(20,257)	(3,293)
Deferred revenues	2,744	(223)
Other current liabilities	(20,432)	10,483
Net changes in other noncurrent assets and liabilities	19,988	12,075
Net cash provided by operations	234,332	162,811
CASH USED IN INVESTING ACTIVITIES:
Capital expenditures	(298,655)	(290,773)
Increase in restricted cash	0	(9,449)
Proceeds from disposals of property, plant and equipment	42,056	9,247
Net cash used in investing activities	(256,599)	(290,975)
CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES:
Proceeds from borrowings	0	493,415
Repayments of borrowings	0	(139,609)
Excess tax benefits from share-based compensation	157	1,142
Proceeds from exercise of share options	2,180	0
Other	1,820	0
Net cash provided by financing activities	4,157	354,948
(DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(18,110)	226,784
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	1,024,008	438,853
CASH AND CASH EQUIVALENTS, END OF PERIOD	$ 1,005,898	$ 665,637