Fair Value of Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2012

Fair Value of Financial Instruments

Financial assets and liabilities measured at fair value on a recurring basis

	Fair Value Measurements at June 30, 2012 Using
Description	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Cash Equivalents:
Money market funds	$	49,917	$	—	$	—	$	49,917
U.S. Treasury bills	16,241		—		—		16,241
Total cash equivalents	$	66,158	$	—	$	—	$	66,158
Short-term Investments:
Corporate bonds	$	—	$	63,154	$	—	$	63,154
Municipal bonds	—		32,532		—		32,532
U.S. government bonds	12,655		—		—		12,655
Asset-backed securities	—		10,665		—		10,665
Variable-rate demand notes	—		8,981		—		8,981
U.S. Treasury bills	7,150		—		—		7,150
International government bonds	—		2,110		—		2,110
U.S. government agency	—		900		—		900
Total short-term investments	$	19,805	$	118,342	$	—	$	138,147
Long-term Investments:
Auction rate securities	$	—	$	—	$	11,028	$	11,028
Total long-term investments	$	—	$	—	$	11,028	$	11,028
Total	$	85,963	$	118,342	$	11,028	$	215,333
Liabilities:
Derivative instruments	$	—	$	1,256	$	—	$	1,256
Total	$	—	$	1,256	$	—	$	1,256

	Fair Value Measurements at December 31, 2011 Using
Description	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Cash Equivalents:
Money market funds	$	50,851	$	—	$	—	$	50,851
Total cash equivalents	$	50,851	$	—	$	—	$	50,851
Short-term Investments:
Corporate bonds	$	—	$	75,060	$	—	$	75,060
Municipal bonds	—		56,984		—		56,984
Variable-rate demand notes	—		41,280		—		41,280
U.S. government agency	—		19,836		—		19,836
U.S. Treasury bills	8,600		—		—		8,600
Asset-backed securities	—		5,739		—		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	$	11,107	$	201,419	$	—	$	212,526
Long-term Investments:
Auction rate securities	$	—	$	—	$	17,477	$	17,477
Total long-term investments	$	—	$	—	$	17,477	$	17,477
Total	$	61,958	$	201,419	$	17,477	$	280,854
Liabilities:
Derivative instruments	$	—	$	1,998	$	—	$	1,998
Contingent consideration	—		—		876		876
Total	$	—	$	1,998	$	876	$	2,874

Summary of quantitative information about level 3 fair value measurements

Description	Fair Value at June 30, 2012 (000s)		Valuation Technique	Unobservable Input	Weighted Average
Auction rate securities	$	11,028	Discounted cash flow	Estimated yield	1.06	%
				Expected holding period	10 years
				Estimated discount rate	2.92	%

Summary of activity in Level 3 financial instruments

Assets

Auction Rate Securities	Three Months Ended			Six Months Ended
Beginning balance	$	17,729		$	17,477
Settlements	(6,650		)	(6,700		)
Gains (losses) included in other comprehensive income	(51		)	251
Balance at June 30, 2012	$	11,028		$	11,028

Liabilities

Contingent Consideration (1)	Six Months Ended
Beginning balance	$	876
Gain recognized in earnings (2)	(876		)
Balance at June 30, 2012	$	—