CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
CASH PROVIDED BY OPERATIONS:
Net income	$ 68,134	$ 49,517
Adjustments to reconcile net income to net cash provided by operations:
Depreciation and amortization	64,616	58,966
Deferred income taxes	(396)	(137)
Provision for pension and postretirement benefits	7,332	7,571
Share-based compensation expense	7,530	5,165
Loss (gain) on disposals of property, plant and equipment	308	(56)
Postretirement benefit claims paid	(881)	(738)
Contributions to pension plans	(249)	(22,542)
Asset impairment charges	0	2,896
Changes in current assets and liabilities:
Receivables - trade and other	(15,081)	(43,448)
Prepaid expenses and other current assets	9,339	9,231
Accounts payable	(1,655)	(4,864)
Accrued income taxes	(11,950)	2,772
Deferred revenues	(2,090)	150
Other current liabilities	(23,778)	(14,279)
Net changes in other noncurrent assets and liabilities	2,000	13,077
Net cash provided by operations	103,179	63,281
CASH USED IN INVESTING ACTIVITIES:
Capital expenditures	(111,965)	(138,105)
Increase in restricted cash	0	(10,621)
Proceeds from disposals of property, plant and equipment	2,387	928
Net cash used in investing activities	(109,578)	(147,798)
CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES:
Repayments of borrowings	0	(12,312)
Excess tax benefits from share-based compensation	112	276
Proceeds from exercise of share options	1,531	214
Net cash provided by (used in) financing activities	1,643	(11,822)
DECREASE IN CASH AND CASH EQUIVALENTS	(4,756)	(96,339)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	1,024,008	438,853
CASH AND CASH EQUIVALENTS, END OF PERIOD	$ 1,019,252	$ 342,514