Note 7. Investments

All of our investments are classified as available-for-sale. The amortized cost and estimated fair value of our investments are as follows:


	December 31, 2011
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(In thousands)
Municipal bonds	$	261,937	$	1,000	$	(144	)	$	262,793
Variable-rate demand notes		56,540		0		0			56,540
Corporate bonds		49,143		115		(250	)		49,008
Auction-rate securities		58,575		0		(5,984	)		52,591

Total	$	426,195	$	1,115	$	(6,378	)	$	420,932



	December 31, 2010
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(In thousands)
Municipal bonds	$	290,284	$	1,538	$	(526	)	$	291,296
Variable-rate demand notes		94,849		0		0			94,849
Corporate bonds		18,863		114		(11	)		18,966
Auction-rate securities		77,150		0		(8,505	)		68,645

Total	$	481,146	$	1,652	$	(9,042	)	$	473,756

Included in our Short-term investments balance as of December 31, 2011 and 2010 were interest receivable of $2.9 million and $3.7 million, respectively, and other investments of $12.9 million and $15.4 million, respectively, which are excluded from the tables above.

The maturities of our investments as of December 31, 2011 are as follows:


	Amortized Cost		Fair Value
	(In thousands)
Due in less than one year	$	121,560	$	121,889
Due after 1 through 5 years		200,515		200,907
Due after 5 through 10 years		2,800		2,800
Due after 10 years		101,320		95,336

Total	$	426,195	$	420,932

Securities with contractual maturities greater than five years consist of auction-rate securities and variable-rate demand notes. We primarily classify auction-rate securities as Long-term investments in our Consolidated Balance Sheets as they are not readily available to us due to failed auctions in the marketplace. Auction rate securities that have been called as of the date of this Annual Report on Form 10-K are classified as short-term based on their expected redemption dates. We classify variable-rate demand notes as Short-term investments in our Consolidated Balance Sheets as they are payable on demand.

The breakdown of investments with unrealized losses as of December 31, 2011 is as follows:


	In Loss Position for Less Than 12 Months					In Loss Position for 12 Months or Greater					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(In thousands)
Municipal bonds	$	47,097	$	(144	)	$	0	$	0		$	47,097	$	(144	)
Corporate bonds		17,515		(250	)		0		0			17,515		(250	)
Auction-rate securities		0		0			42,891		(5,984	)		42,891		(5,984	)

Total	$	64,612	$	(394	)	$	42,891	$	(5,984	)	$	107,503	$	(6,378	)

The unrealized losses related to municipal and corporate bonds are primarily due to fluctuations in interest rates and quoted market prices. The unrealized losses related to auction-rate securities are primarily due to our estimates about the anticipated term and yield of these investments given the lack of an active market. We review our investment portfolio for possible impairment on a quarterly basis. Impairment is based on an analysis of factors that may have adverse effects on the fair value of the investment. Factors considered in determining whether a loss is temporary include our intent to sell the security, our ability to hold the security to recovery of its amortized cost, and our assessment of the credit quality of the security, including whether we expect to recover the amortized cost of the security.

See additional disclosures regarding the fair value of our investments in Note 6 above.