Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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- Definition

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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FAIR VALUE - Narrative (Details) - Convertible senior notes - USD ($)	Mar. 31, 2019	Dec. 31, 2018	Sep. 09, 2014
Schedule of Cash and Cash Equivalents and Marketable Securities [Line Items]
Interest rate			2.50%
Par value of debt		$ 345,000,000	$ 345,000,000
Fair Value \| Level 2
Schedule of Cash and Cash Equivalents and Marketable Securities [Line Items]
Estimated fair value of debt	$ 277,100,000	$ 231,800,000