Fair Value Measurements - Estimated Fair Value and Carrying Value of 2019, 2020 and 2023 Notes (Detail) - USD ($) $ in Thousands	Aug. 03, 2019	Feb. 02, 2019
Convertible senior notes due 2019
Fair Value Balance Sheet Grouping Financial Statement Captions
Convertible senior notes, Fair Value		$ 334,756
Convertible senior notes, Carrying Value		344,146
Convertible senior notes due 2020
Fair Value Balance Sheet Grouping Financial Statement Captions
Convertible senior notes, Fair Value	$ 282,338	260,258
Convertible senior notes, Carrying Value	281,868	272,919
Convertible senior notes due 2023
Fair Value Balance Sheet Grouping Financial Statement Captions
Convertible senior notes, Fair Value	263,595	230,684
Convertible senior notes, Carrying Value	$ 261,848	$ 253,689

Including the current and noncurrent portions, carrying value as of the balance sheet date of a written promise to pay a note, initially due after one year or beyond the operating cycle if longer, which can be exchanged for a specified amount of one or more securities (typically common stock), at the option of the issuer or the holder.

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-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 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-SubTopic 210
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-Section S99
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

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