Income Taxes - Components of Comprehensive Provision for Income Taxes Allocation (Detail) (USD $)	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Comprehensive provision (benefit) for income taxes allocable to:
Continuing operations	$ (12,658,000)	$ 7,994,000
Discontinued operations		600,000
Other comprehensive income (loss):
Marketable securities	18,300,000	(13,900,000)
Currency translation	(2,900,000)	2,000,000
Total	3,000,000	(3,100,000)
Defined Benefit Pension Plans [Member]
Other comprehensive income (loss):
OPEB plans	400,000	300,000
OPEB [Member]
Other comprehensive income (loss):
OPEB plans	$ (100,000)	$ (100,000)

Tax effect allocated to a disposal group that is classified as a component of the entity reported as a separate component of income before extraordinary items. Includes the tax effects of the following: income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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-Name Statement of Financial Accounting Standard (FAS)

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+ Details

- Definition

The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations.

+ References+ Details

- Definition

Tax effect, net of reclassification adjustments, of the change in the balance sheet adjustment that results from the process of translating subsidiary financial statements and foreign equity investments into the reporting currency of the reporting entity. Also includes the following: gain (loss) on foreign currency forward exchange contracts; 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; and gain (loss) on a derivative instrument or nonderivative financial instrument that may give rise to a foreign currency transaction gain (loss) that has been designated and qualified as a hedging instrument for hedging of the foreign currency exposure of a net investment in a foreign operation.

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