Short- and Long-Term Investments and Investments on Deposit for Licensure (Tables)

12 Months Ended

Dec. 31, 2011

Short- and Long-Term Investments and Investments on Deposit for Licensure [Abstract]

Reconciliation schedule of available-for-sale securities from cost basis to fair value

The amortized cost, gross unrealized holding gains, gross unrealized holding losses and fair value for available-for-sale short- and long-term investments and investments on deposit for licensure held at December 31, 2011 were as follows:

	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Fair Value
Auction rate securities	$	12,550	$	—	$	999	$	11,551
Certificates of deposit		118,081		13		—		118,094
Commercial paper		172,657		2		95		172,564
Corporate bonds		565,382		2,852		1,510		566,724
Debt securities of government sponsored entities		289,901		742		100		290,543
Equity index funds		40,146		1,355		658		40,843
Money market funds		15,067		—		—		15,067
Municipal bonds		382,049		16,978		1		399,026
U.S. Treasury securities		26,045		80		1		26,124
Total	$	1,621,878	$	22,022	$	3,364	$	1,640,536

The amortized cost, gross unrealized holding gains, gross unrealized holding losses and fair value for available-for-sale short- and long-term investments and investments on deposit for licensure held at December 31, 2010 were as follows:

	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Fair Value
Auction rate securities	$	22,650	$	—	$	1,357	$	21,293
Certificates of deposit		13,651		—		—		13,651
Commercial paper		14,797		—		4		14,793
Corporate bonds		235,775		2,327		186		237,916
Debt securities of government sponsored entities		331,893		623		465		332,051
Federally insured corporate bonds		21,097		360		3		21,454
Money market funds		20,315		—		—		20,315
Municipal bonds		301,234		1,145		1,562		300,817
U.S. Treasury securities		21,592		130		1		21,721
Total	$	983,004	$	4,585	$	3,578	$	984,011

Schedule of amortized cost and fair value of available-for-sale debt securities by contractual maturity

The amortized cost and fair value of investments in debt securities, by contractual maturity, for available-for-sale short- and long-term investments and investments on deposit for licensure held at December 31, 2011 were as follows:

	Amortized Cost		Fair Value
Maturing within one year	$	551,658	$	552,129
Maturing between one year and five years		739,375		741,922
Maturing between five years and ten years		192,856		205,905
Maturing in greater than ten years		97,845		99,737
Total	$	1,581,734	$	1,599,693

Schedule of available-for-sale securities with unrealized losses not deemed to be other-than-temporarily impaired

	Less than 12 Months						12 Months or Greater
	Fair Value		Gross Unrealized Holding Losses		Total Number of Securities		Fair Value		Gross Unrealized Holding Losses		Total Number of Securities
2011:
Auction rate securities	$	—	$	—		—	$	11,551	$	999		3
Commercial paper		149,074		95		12		—		—		—
Corporate bonds		185,231		1,498		98		8,989		12		1
Debt securities of government sponsored entities		103,766		100		28		—		—		—
Equity index funds		17,021		658		5		—		—		—
Municipal bond		5,129		1		1		—		—		—
U.S. Treasury securities		12,025		1		3		—		—		—
Total temporarily impaired securities	$	472,246	$	2,353		147	$	20,540	$	1,011		4
	Less than 12 Months						12 Months or Greater
	Fair Value		Gross Unrealized Holding Losses		Total Number of Securities		Fair Value		Gross Unrealized Holding Losses		Total Number of Securities
2010:
Auction rate securities	$	—	$	—		—	$	21,293	$	1,357		6
Commercial paper		19,495		4		8		—		—		—
Corporate bonds		71,278		186		37		—		—		—
Debt securities of government sponsored entities		86,881		465		29		—		—		—
Federally insured corporate bond		4,036		3		1		—		—		—
Municipal bonds		160,860		1,562		64		—		—		—
U.S. Treasury securities		9,564		1		3		—		—		—
Total temporarily impaired securities	$	352,114	$	2,221		142	$	21,293	$	1,357		6