Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Comprehensive Income
Net income	$ 168,618	$ 151,812	$ 314,873	$ 278,327
Other comprehensive income:
Foreign currency translation			3,925	26,363
Pension and other post-retirement benefit adjustments:
Recognition of prior service credit, net of tax			(2,474)	(2,519)
Recognition of actuarial loss, net of tax			22,143	16,028
Total other comprehensive income			23,594	39,872
Comprehensive income	163,693	163,361	338,467	318,199
Comprehensive Income (Textual) [Abstract]
Comprehensive income	$ 163,693	$ 163,361	$ 338,467	$ 318,199

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The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the economic entity, including both controlling (parent) and noncontrolling interests. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, including any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

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The adjustment out of other comprehensive income for prior service costs recognized as a component of net period benefit cost during the period, after tax.

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Change in the balance sheet adjustment that results from the process of translating subsidiary financial statements and foreign equity investments into functional currency of the reporting entity for the period being reported, net of tax. If an entity's functional currency is a foreign currency, translation adjustments result from the process of translating that entity's financial statements into the reporting currency. Includes gain (loss) on foreign currency forward exchange contracts. Includes foreign currency transactions designated as hedges of net investment in a foreign entity and intercompany foreign currency transactions that are of a long-term nature, when the entities to the transaction are consolidated, combined, or accounted for by the equity method in the reporting enterprise's financial statements. Includes the gain (loss) on a derivative instrument or nonderivative financial instrument that may give rise to a foreign currency transaction gain (loss) and that have been designated and have qualified as hedging instruments for hedges of the foreign currency exposure of a net investment in a foreign operation.

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The adjustment out of other comprehensive income for actuarial gains or losses recognized as a component of net periodic benefit cost during the period, after tax.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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