Summary Of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2012

Schedule Of Assets And Liabilities Measured At Fair Value On Recurring Basis

The following table summarizes the assets and liabilities measured at fair value on a recurring basis as of March 31, 2012 and December 31, 2011 (in thousands):



	Fair value measurements as of
	March 31, 2012
	Total		Level 1		Level 2		Level 3
Assets:
Cash and cash equivalents	$	73,401	$	12,983	$	60,418	$	—
Short-term investments	231,225		3,000		228,225		—
Restricted cash	10,673		10,673		—		—
Deferred compensation plan assets	9,745		2,143		7,602		—
Embedded derivative (2)	2,441		—		—		2,441
	$	327,485	$	28,799	$	296,245	$	2,441
Liabilities:
Deferred compensation plan liabilities	$	9,745	$	2,143	$	7,602	$	—
Loss protection liability carried at fair value (3)	50,366		—		—		50,366
	$	60,111	$	2,143	$	7,602	$	50,366

	Fair value measurements as of
	December 31, 2011
	Total		Level 1 (1)		Level 2 (1)		Level 3
Assets:
Cash and cash equivalents	$	99,859	$	61,850	$	38,009	$	—
Short-term investments	104,206		—		104,206		—
Restricted cash	10,519		10,519		—		—
Deferred compensation plan assets	8,192		990		7,202		—
Embedded derivative (2)	7,690		—		—		7,691
	$	230,466	$	73,359	$	149,417	$	7,691
Liabilities:
Deferred compensation plan liabilities	$	8,192	$	990	$	7,202	$	—
Loss protection liability carried at fair value (3)	46,419		—		—		46,419
	$	54,611	$	990	$	7,202	$	46,419

(1) During 2012, the company changed how it categorizes amounts within the fair value hierarchy and thus, certain amounts now reported as Level 2 fair value instruments at March 31, 2012 were previously shown as Level 1 and have been reclassified.

(2) The embedded derivative is associated with the promissory note related to the Revenue Sharing Obligation, or RSO, issued in connection with the Termination Agreement (see Note 6). The embedded derivative represents embedded options which would allow Amylin to discharge all or a portion of the obligation under certain circumstances (see Note 8 for the terms of the RSO). The fair value of the embedded derivative is calculated using a probability weighted expected return method, or PWERM. Significant inputs to the valuation include the following:


•	Management's estimates of total revenue of exenatide products over the period in which the RSO is to be repaid;


•	A variety of scenarios under which management estimated the probability that BYDUREON^TM (exenatide for extended-release injectable suspension) would be approved by the U.S. Food and Drug Administration , or the FDA, prior to June 30, 2014;


•	A variety of scenarios under which all exenatide products would be removed from certain geographic markets for safety or efficacy reasons and remain unsalable for four consecutive years.

(3) The loss protection liability arose in connection with the Termination Agreement (see Note 6) and relates to payments required to be made prior to the final transfer of the markets outside the United States from Lilly to Amylin. The maximum that could be paid under the loss protection liability is $60.0 million over the period January 1, 2012 through December 31, 2013. The fair value of the loss protection liability is calculated using a PWERM. Significant inputs to the valuation include the following:


•	Financial projections for markets outside the United States, or the OUS markets, which were provided to Amylin's management by Lilly;


•	A variety of scenarios under which management estimated the extent to which these financial projections would be achieved, and the resulting payouts of the amounts that could be made for the twelve months ended December 31, 2012 and 2013.

The greatest drivers of variability in this liability are the estimated losses subject to the guarantee and variations in the discount rates used in the valuation.

Schedule Of Antidilutive Instruments Excluded From Calculation Of Basic And Diluted Earnings Per Share

Shares used in calculating basic and diluted net loss per common share exclude the following common share equivalents (in thousands):



	Three months ended, March 31,
	2012		2011
Antidilutive options and awards to purchase common stock	974		545
Antidilutive shares underlying convertible senior notes	9,416	(1)	15,238
	10,390		15,783


(1)	In April 2011, we repaid $200 million of convertible senior notes which matured on April 15, 2011. There were 5.8 million antidilutive shares underlying the repaid convertible senior notes.

Schedule Of Estimated Stock-Based Compensation

Total employee non-cash stock-based compensation expense by operating statement classification was as follows (in thousands):



	Three months ended March 31,
	2012		2011
Selling, general and administrative expenses	$	6,302	$	5,539
Research and development expenses	2,856		2,378
	$	9,158	$	7,917

Schedule Of Non-Cash ESOP And Expense By Operating Statement Classification

The breakdown of non-cash ESOP and 401(k) expense by operating statement classification for each of the three month periods ended March 31, 2012 and 2011 is presented below (in thousands):



	Three months ended, March 31,
	2012		2011
Selling, general and administrative expenses	$	4,383	$	2,536
Research and development expenses	3,315		1,702
	$	7,698	$	4,238

Schedule of Assets and Liabilities Measured at Fair Value using Unobservable Inputs Level 3 [Table Text Block]

The following table presents a reconciliation of the assets and liabilities measured at fair value on a quarterly basis using significant unobservable inputs (Level 3) from January 1, 2012 to March 31, 2012 (in thousands):



	Derivative Asset - Embedded Option carried at fair value
Assets:
Embedded derivative:
Balance at January 1, 2012	$	7,691
Adjustment to fair value charged to interest and other expense, net	(5,250		)
Balance at March 31, 2012	$	2,441


	Loss Protection Liability carried at fair value
Liabilities:
Loss protection liability carried at fair value:
Balance at January 1, 2012	$	46,419
Adjustment to fair value charged to operating expense	3,947
Balance at March 31, 2012	$	50,366