FAIR VALUE MEASUREMENTS (Tables)

9 Months Ended

Sep. 30, 2020

Fair Value Disclosures [Abstract]

Schedule of fair value measurements along with the level within the fair value hierarchy in which the fair value measurements fall

The following table presents the Company’s fair value measurements as of September 30, 2020 along with the level within the fair value hierarchy in which the fair value measurements in their entirety fall.

(In thousands)	Fair Value at September 30, 2020		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash, cash equivalents, and restricted cash	​		​		​		​
Cash and money market	$	456,701	$	456,701	$	—	$	—
U.S. government agency securities	349,977		—		349,977		—
Restricted cash	291		291		—		—
Marketable securities
Corporate bonds	192,621		—		192,621		—
U.S. government agency securities	257,162		—		257,162		—
Certificates of deposit	10,001		—		10,001		—
Asset backed securities	15,122		—		15,122		—
Equity Securities	1,418		1,418		—		—
Liabilities
Contingent consideration	(2,638)		—		—		(2,638)
Total	$	1,280,655	$	458,410	$	824,883	$	(2,638)

The following table presents the Company’s fair value measurements as of December 31, 2019 along with the level within the fair value hierarchy in which the fair value measurements in their entirety fall.​

(In thousands)	Fair Value at December 31, 2019		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash and cash equivalents	​		​		​		​
Cash and money market	$	146,932	$	146,932	$	—	$	—
U.S. government agency securities	30,322		—		30,322		—
Restricted cash	274		274		—		—
Marketable securities
U.S. government agency securities	140,682		—		140,682		—
Corporate bonds	4,003		—		4,003		—
Equity securities	1,716		1,716		—		—
Liabilities
Contingent consideration	(2,879)		—		—		(2,879)
Total	$	321,050	$	148,922	$	175,007	$	(2,879)

Schedule of fair value of contingent consideration

The following table provides a roll-forward of the fair values of the contingent consideration, which includes Level 3 measurements:

(In thousands)	Contingent consideration
Balance, January 1, 2020	$	(2,879)
Changes in fair value	—
Gains (losses) recognized in earnings	—
Payments	241
Balance, September 30, 2020	$	(2,638)

Schedule of fair value of long-term debt and convertible notes

The following table summarizes the Company’s outstanding convertible notes and long-term debt:​

​	September 30, 2020				December 31, 2019
(In thousands)	Carrying Amount (1)		Fair Value		Carrying Amount (1)		Fair Value
2028 Convertible notes (2)	$	796,463	$	1,251,085	$	—	$	—
2027 Convertible notes (2)	506,294		881,631		483,909		843,741
2025 Convertible notes (2)	252,210		494,627		319,696		592,482
Construction loan (3)	23,962		23,962		24,866		24,866

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(1)The carrying amounts presented are net of debt discounts and debt issuance costs (see Note 12 and Note 15 of the condensed consolidated financial statements for further information).​

(2)The fair values are based on observable market prices for this debt, which is traded in active markets and therefore is classified as a Level 2 fair value measurement. A portion of the 2025 convertible notes were settled in 2020 resulting in a decrease in the liability.​

(3)The carrying amount of the construction loan approximates fair value due to the short-term nature of this instrument. The construction loan is privately held with no public market for this debt and therefore is classified as a Level 3 fair value measurement. The change in the fair value was due to payments made on the loan resulting in a decrease in the liability.