Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 1

-Article 5

+ Details

- Definition

This item represents investments in debt securities which are categorized as held-to-maturity and that have scheduled maturities within one year of the balance sheet date or the normal operating cycle, whichever is longer; such investments are measured at amortized cost (carrying value). The held-to-maturity category is for those securities that the Entity has the positive intent and ability to hold until maturity.

+ References

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+ Details

- Definition

This item represents investments in debt securities which are categorized as held-to-maturity and that have scheduled maturities more than one year from the balance sheet date or operating cycle, if longer; such investments are measured at amortized cost (carrying value). The held-to-maturity category is for those securities that the Entity has the positive intent and ability to hold until maturity.

+ References+ Details

Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 419,696	$ 378,358	$ 511,078	$ 424,155
Short-term investments	110,585	100,676
Long-term investments	40,142	50,305
Fair value assumption, interest rate	6.05%
Minimum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long term investment maturities	Nov. 30, 2014
Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long term investment maturities	Dec. 15, 2014
Fair Value \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	419,696	378,358
Fair Value \| Level 1 \| 6.95% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	363,067	376,610
Fair Value \| Level 2 \| 6.7% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	585,423	582,744
Fair Value \| Government backed securities \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments	110,585	100,676
Long-term investments	40,175	50,339
Book Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	419,696	378,358
Book Value \| 6.95% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	342,000	342,000
Book Value \| 6.7% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	532,256	532,194
Book Value \| Government backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments	110,585	100,676
Long-term investments	$ 40,142	$ 50,305