FAIR VALUE MEASUREMENTS (Tables)

12 Months Ended

Dec. 31, 2015

Fair Value of Financial Assets and Liabilities

The tables below present the fair value of these financial assets and liabilities determined using the following input levels.

	Fair Value Measurements at December 31, 2015
	Quoted Price in Active Markets For Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Cash and cash equivalents:
Overnight deposits	$	290,731	$	—	$	—	$	290,731
Money market instruments		—		106,309		—		106,309
Total cash and cash equivalents		290,731		106,309		—		397,040
Available-for-sale securities:
Short-term:
Certificates of deposit		—		56,951		—		56,951
Corporate debt securities		—		42,673		—		42,673
Commercial paper		—		12,733		—		12,733
U.S. government agency securities		—		83,222		—		83,222
Long-term:
Certificates of deposit		—		6,969		—		6,969
Corporate debt securities		—		315,240		—		315,240
U.S. government agency securities		—		103,316		—		103,316
Greek government-issued bonds		—		127		—		127
Total available-for-sale securities		—		621,231		—		621,231
Other Current Assets:
Nonqualified Deferred Compensation Plan assets		—		440		—		440
Forward foreign currency exchange contract ⁽¹⁾		—		10,478		—		10,478
Restricted investments ⁽²⁾		—		7,348		—		7,348
Total other current assets		—		18,266		—		18,266
Other Assets:
Nonqualified Deferred Compensation Plan assets		—		6,362		—		6,362
Forward foreign currency exchange contract ⁽¹⁾		—		3,533		—		3,533
Strategic investment ⁽⁴⁾		18,056		—		—		18,056
Total other assets		18,056		9,895		—		27,951
Total assets	$	308,787	$	755,701	$	—	$	1,064,488
Liabilities:
Current Liabilities:
Nonqualified Deferred Compensation Plan liability	$	1,151	$	440	$	—	$	1,591
Forward foreign currency exchange contract⁽¹⁾		—		2,008		—		2,008
Contingent acquisition consideration payable		—		—		52,946		52,946
Total current liabilities		1,151		2,448		52,946		56,545
Other long-term liabilities:
Nonqualified Deferred Compensation Plan liability		24,341		6,362		—		30,703
Forward foreign currency exchange contract⁽¹⁾		—		3,057		—		3,057
Contingent acquisition consideration payable		—		—		32,663		32,663
Total other long-term liabilities		24,341		9,419		32,663		66,423
Total liabilities	$	25,492	$	11,867	$	85,609	$	122,968

	Fair Value Measurements at December 31, 2014
	Quoted Price in Active Markets For Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Cash and cash equivalents:
Overnight deposits	$	225,159	$	—	$	—	$	225,159
Money market instruments		—		650,327		—		650,327
Total cash and cash equivalents		225,159		650,327		—		875,486
Available-for-sale securities:
Short-term:
Certificates of deposit		—		54,174		—		54,174
Corporate debt securities		—		15,532		—		15,532
Long-term:
Certificates of deposit		—		18,129		—		18,129
Corporate debt securities		—		79,604		—		79,604
Greek government-issued bonds		—		123		—		123
Total available-for-sale securities		—		167,562		—		167,562
Other Current Assets:
Nonqualified Deferred Compensation Plan assets		—		514		—		514
Forward foreign currency exchange contract ⁽¹⁾		—		10,513		—		10,513
Restricted investments ⁽²⁾		—		2,354		—		2,354
Embedded derivative ⁽³⁾		—		—		2,386		2,386
Total other current assets		—		13,381		2,386		15,767
Other Assets:
Nonqualified Deferred Compensation Plan assets		—		5,112		—		5,112
Restricted investments ⁽²⁾		—		5,387		—		5,387
Strategic investment ⁽⁴⁾		30,811		—		—		30,811
Total other assets		30,811		10,499		—		41,310
Total assets	$	255,970	$	841,769	$	2,386	$	1,100,125
Liabilities:
Current Liabilities:
Nonqualified Deferred Compensation Plan liability	$	1,790	$	514	$	—	$	2,304
Forward foreign currency exchange contract ⁽¹⁾		—		12		—		12
Contingent acquisition consideration payable		—		—		3,895		3,895
Total current liabilities		1,790		526		3,895		6,211
Other long-term liabilities:
Nonqualified Deferred Compensation Plan liability		18,453		5,112		—		23,565
Contingent acquisition consideration payable		—		—		38,767		38,767
Total other long-term liabilities		18,453		5,112		38,767		62,332
Total liabilities	$	20,243	$	5,638	$	42,662	$	68,543

(1)	See Note 12 to these Consolidated Financial Statements for further information regarding the derivative instruments.

(2)	The restricted investments at December 31, 2015 and 2014 secure the Company’s irrevocable standby letter of credit obtained in connection with certain commercial agreements.

(3)	The embedded derivative represents the fair value of the conversion feature of a promissory note which may be settled in the issuer’s underlying shares.

(4)	The Company has investments in marketable equity securities measured using quoted prices in an active market that are considered strategic investments. See Note 7 to these Consolidated Financial Statements for additional discussion regarding the Company’s strategic investments.

Liabilities Measured at Fair Value Using Level 3 Inputs

Contingent acquisition consideration payable at December 31, 2014	$	42,662
Addition of contingent consideration payable related to the Prosensa acquisition		71,402
Reversal of contingent liability related to no early FDA approval for Kyndrisa		(39,726	)
Changes in the fair value of other acquisition contingent consideration payable		11,271
Contingent acquisition consideration payable at December 31, 2015	$	85,609

Asset Retirement Obligation Liability and Corresponding Capital Asset

Asset retirement obligations at December 31, 2014	$	3,765
Accretion expense		148
Additions		820
Settlements		(29	)
Asset retirement obligations at December 31, 2015	$	4,704