FAIR VALUE OF FINANCIAL INSTRUMENTS

6 Months Ended

Jun. 30, 2011

FAIR VALUE OF FINANCIAL INSTRUMENTS

FAIR VALUE OF FINANCIAL INSTRUMENTS

8.     FAIR VALUE OF FINANCIAL INSTRUMENTS

• The following table summarizes the estimated fair values of the Company's financial instruments as of June 30, 2011 and December 31, 2010:

	As of June 30, 2011						As of December 31, 2010
	Carrying Value			Fair Value			Carrying Value			Fair Value
Cash equivalents	$	59,842		$	59,842		$	91,448		$	91,448
Marketable securities		12,124			12,124			8,166			8,166
Long-term debt		(4,546,789	)		(4,766,900	)		(3,595,277	)		(4,174,561	)

• The following table summarizes the Company's marketable securities by major security type as of June 30, 2011 and December 31, 2010:

	As of June 30, 2011									As of December 31, 2010
					Gross Unrealized									Gross Unrealized
	Cost Basis		Fair Value							Cost Basis		Fair Value
					Gains		Losses							Gains		Losses
Sanitas ordinary shares	$	9,319		9,170	$	—	$	(149	)	$	—		—	$	—	$	—
Corporate bonds		2,942		2,954		12		—			6,234		6,340		106		—
Government-sponsored enterprise securities		—		—		—		—			1,825		1,826		1		—
	$	12,261	$	12,124	$	12	$	(149	)	$	8,059	$	8,166	$	107	$	—

• All marketable debt securities held as of June 30, 2011 mature within one year. Gross gains and losses realized on the sale of marketable debt securities were not material in the three-month or six-month periods ended June 30, 2011 and 2010.