Note 8. Restricted Cash and Investments (Details) - Available For Sale (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	$ 102,457	$ 183,357
Available-for-sale securities, gross unrealized gains	155	84
Available-for-sale securities, gross unrealized losses	34	1,103
Available-for-sale Securities, estimated fair value	102,578	182,338
Foreign Government Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	4,138	9,128
Available-for-sale securities, gross unrealized gains	4	1
Available-for-sale securities, gross unrealized losses	0	9
Available-for-sale Securities, estimated fair value	4,142	9,120
US Government Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	2,000	1,999
Available-for-sale securities, gross unrealized gains	4	15
Available-for-sale securities, gross unrealized losses	0	0
Available-for-sale Securities, estimated fair value	2,004	2,014
Restricted Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	241,718	148,559
Available-for-sale securities, gross unrealized gains	59,498	30,256
Available-for-sale securities, gross unrealized losses	0	0
Available-for-sale Securities, estimated fair value	301,216	178,815
Contractual Maturities Of Available-For-Sale Marketable Securities, Range End	24 years	24 years
Contractual Maturities Of Available-For-Sale Marketable Securities, Range Start	15 years	16 years
Restricted Investments [Member] \| Foreign Government Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	188,350	132,734
Available-for-sale securities, gross unrealized gains	47,921	23,102
Available-for-sale securities, gross unrealized losses	0	0
Available-for-sale Securities, estimated fair value	236,271	155,836
Restricted Investments [Member] \| US Government Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	53,368	15,825
Available-for-sale securities, gross unrealized gains	11,577	7,154
Available-for-sale securities, gross unrealized losses	0	0
Available-for-sale Securities, estimated fair value	$ 64,945	$ 22,979

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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