Cash, Cash Equivalents and Investments (Tables)

3 Months Ended

Mar. 31, 2012

Cash, Cash Equivalents and Investments

Schedule of cash, cash equivalents, and investments

	March 31, 2012
	Cost		Gross Unrealized Losses			Gross Unrealized Gains		Fair Value
Cash and Cash Equivalents:
Cash on hand	$	43,251	$	—		$	—	$	43,251
Available-for-sale securities:
Money market funds	42,887		—			—		42,887
U.S. Treasury bills	11,899		—			1		11,900
Total available-for-sale securities	54,786		—			1		54,787
Total cash and cash equivalents	$	98,037	$	—		$	1	$	98,038
Short-term Investments:
Available-for-sale securities:
Corporate bonds	$	83,335	$	(43	)	$	307	$	83,599
Municipal bonds	67,251		(4		)	92		67,339
Variable-rate demand notes	48,310		—			—		48,310
U.S. government bonds	12,652		(13		)	—		12,639
Asset-backed securities	10,034		(1		)	9		10,042
U.S. government agency	5,901		—			1		5,902
U.S. Treasury bills	5,349		—			—		5,349
International government bonds	2,119		—			—		2,119
Total short-term investments	$	234,951	$	(61	)	$	409	$	235,299
Long-term Investments:
Available-for-sale securities:
Auction rate securities	$	19,175	$	(1,446	)	$	—	$	17,729
Total long-term investments	$	19,175	$	(1,446	)	$	—	$	17,729

	December 31, 2011
	Cost		Gross Unrealized Losses			Gross Unrealized Gains		Fair Value
Cash and Cash Equivalents:
Cash on hand	$	44,113	$	—		$	—	$	44,113
Available-for-sale securities:
Money market funds	50,851		—			—		50,851
Total cash and cash equivalents	$	94,964	$	—		$	—	$	94,964
Short-term Investments:
Available-for-sale securities:
Corporate bonds	$	75,189	$	(363	)	$	234	$	75,060
Municipal bonds	56,915		(12		)	81		56,984
Variable-rate demand notes	41,280		—			—		41,280
U.S. government agency	19,820		(12		)	28		19,836
U.S. Treasury bills	8,600		—			—		8,600
Asset-backed securities	5,743		(5		)	1		5,739
U.S. government bonds	2,507		—			—		2,507
Certificates of deposit	1,570		—			—		1,570
International government bonds	950		—			—		950
Total short-term investments	$	212,574	$	(392	)	$	344	$	212,526
Long-term Investments:
Available-for-sale securities:
Auction rate securities	$	19,225	$	(1,748	)	$	—	$	17,477
Total long-term investments	$	19,225	$	(1,748	)	$	—	$	17,477

Schedule of available-for-sale investments in continuous unrealized loss position by length of time

	Less Than 12 Months					12 Months or Greater					Total
As of March 31, 2012	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Corporate bonds	$	22,814	$	(43	)	$	—	$	—		$	22,814	$	(43	)
Auction rate securities	—		—			17,729		(1,446		)	17,729		(1,446		)
U.S. government bonds	12,639		(13		)	—		—			12,639		(13		)
Municipal bonds	10,367		(4		)	—		—			10,367		(4		)
Asset-backed securities	1,077		(1		)	—		—			1,077		(1		)
	$	46,897	$	(61	)	$	17,729	$	(1,446	)	$	64,626	$	(1,507	)

	Less Than 12 Months					12 Months or Greater					Total
As of December 31, 2011	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Corporate bonds	$	25,438	$	(363	)	$	—	$	—		$	25,438	$	(363	)
Auction rate securities	—		—			17,477		(1,748		)	17,477		(1,748		)
Municipal bonds	10,437		(12		)	—		—			10,437		(12		)
U.S. government agency	5,772		(12		)	—		—			5,772		(12		)
Asset-backed securities	4,539		(5		)	—		—			4,539		(5		)
	$	46,186	$	(392	)	$	17,477	$	(1,748	)	$	63,663	$	(2,140	)

Summarization of contractual underlying maturities of available-for-sale investments

	Cost		Fair Value
Due in one year or less	$	139,344	$	139,480
Due after one year through ten years	110,933		111,146
Due after ten years	58,635		57,189
	$	308,912	$	307,815