FAIR VALUE MEASUREMENTS (Tables)

6 Months Ended

Jun. 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 June 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 June 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	$	457,019	$	457,019	$	—	$	—
U.S. government agency securities	246,907		—		246,907		—
Restricted cash	282		282		—		—
Marketable securities
Corporate bonds	220,561		—		220,561		—
U.S. government agency securities	256,526		—		256,526		—
Certificates of deposit	10,000		—		10,000		—
Asset backed securities	22,259		—		22,259		—
Commercial paper	8,000		—		8,000		—
Equity Securities	1,385		1,385		—		—
Liabilities
Contingent consideration	(2,551)		—		—		(2,551)
Total	$	1,220,388	$	458,686	$	764,253	$	(2,551)

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	328
Balance, June 30, 2020	$	(2,551)

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:​

​	June 30, 2020				December 31, 2019
(In thousands)	Carrying Amount (1)		Fair Value		Carrying Amount (1)		Fair Value
2028 Convertible notes (2)	$	786,711	$	1,101,413	$	—	$	—
2027 Convertible notes (2)	498,707		774,328		483,909		843,741
2025 Convertible notes (2)	248,965		419,015		319,696		592,482
Construction loan (3)	24,263		24,263		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.