Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities:
Net income	$ 13,766	$ 11,582
Depreciation and amortization	97,148	88,446
Other operating activities and non-cash items	(840)	(1,772)
Changes in assets and liabilities	(11,400)	(42,150)
Net cash provided by operating activities	98,674	56,106
Cash flows from investing activities:
Purchases of property, plant and equipment	(112,543)	(121,087)
Proceeds from the sale of property, plant and equipment	24,614	621
Payments from unconsolidated affiliate	8,843	7,914
Other investing activities	(249)	1,683
Net cash used in investing activities	(79,335)	(110,869)
Cash flows from financing activities:
Borrowings under short-term debt	0	20,000
Payments of short-term debt	0	(15,000)
Proceeds from issuance of long-term debt	33,000	158,742
Payments of long-term debt	0	(156,357)
Payments for repurchase of common stock	0	(4,505)
Proceeds from the issuance of stock through share-based compensation plans	0	69
Payments of tax withholding for restricted shares	(90)	(353)
Net cash provided by financing activities	32,910	2,596
Effect of exchange rate fluctuations on cash and cash equivalents	1,405	(1,332)
Net increase (decrease) in cash and cash equivalents	53,654	(53,499)
Cash and cash equivalents, beginning of period	413,048	434,631
Cash and cash equivalents, end of period	$ 466,702	$ 381,132