Fair Value Measurements (Schedule Of Available For Sale Securities) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Cost		$ 12,976	$ 12,552
Gross unrealized losses
Gross Unrealized Gains		106,220	65,214
Fair value		119,196	77,766
Available-for-sale Securities [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Cost	625	5,207	7,786
Gross unrealized losses
Gross Unrealized Gains	334	106,220	65,214
Fair value	959	111,427	73,000
Cost-method Investments [Member]
Fair Value, Option, Qualitative Disclosures Related to Election [Line Items]
Cost		7,769	4,766
Gross unrealized losses
Fair value		$ 7,769	$ 4,766

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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