Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

Reference 2: 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(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_StockRepurchasedDuringPeriodShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Subsequent Events - Additional Information (Detail) - USD ($)			3 Months Ended	35 Months Ended
	Jun. 07, 2019	May 29, 2019	Apr. 30, 2019	Apr. 30, 2019
Subsequent Event [Line Items]
Stock repurchased during period, shares			0	3,985,876
Subsequent Event [Member]
Subsequent Event [Line Items]
Stock repurchased during period, shares	0	0
Subsequent Event [Member] \| Stock Repurchase Program $50.0 Million Authorization [Member]
Subsequent Event [Line Items]
Stock repurchase program, authorization date		May 29, 2019
Subsequent Event [Member] \| Stock Repurchase Program $50.0 Million Authorization [Member] \| Maximum [Member]
Subsequent Event [Line Items]
Amount authorized under stock repurchase program		$ 50,000,000