Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_LongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

SUBSEQUENT EVENTS - Narrative (Details) - Convertible senior notes - USD ($)	Apr. 08, 2020	Mar. 31, 2020	Mar. 11, 2020	Feb. 19, 2020	Dec. 31, 2019
Subsequent Event [Line Items]
Notes remaining		$ 0			$ 194,815,000
Convertible Senior Notes 2.5% And Convertible Senior Notes 5.0%
Subsequent Event [Line Items]
Tender offer to repurchase debt			$ 77,000,000.0
Repurchased aggregate principal amount				$ 188,000,000.0
Convertible Senior Notes 2.5% And Convertible Senior Notes 5.0% \| Subsequent Event
Subsequent Event [Line Items]
Repurchased aggregate principal amount	$ 76,700,000
2.5% Convertible Notes debt 2021
Subsequent Event [Line Items]
Repurchased aggregate principal amount				$ 102,500,000
2.5% Convertible Notes debt 2021 \| Subsequent Event
Subsequent Event [Line Items]
Notes remaining	$ 300,000