Date the declared dividend will be paid, in CCYY-MM-DD format.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

+ Details

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- Definition

The per share amount of a dividend declared, but not paid, as of the financial reporting date.

+ References

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- Definition

Date the holder must own the stock to be entitled to the dividend, in CCYY-MM-DD format.

+ References

No definition available.

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- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

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Subsequent Events- Additional Information (Detail) - $ / shares		1 Months Ended
	Feb. 01, 2019	Aug. 31, 2018	Aug. 31, 2017
Subsequent Event [Line Items]
Dividend Declared payable		Oct. 17, 2018	Oct. 18, 2017
Dividend Declared record		Sep. 12, 2018	Sep. 13, 2017
Subsequent Event [Member]
Subsequent Event [Line Items]
Dividend Declared payable	Apr. 17, 2019
Dividend Declared record	Mar. 13, 2019
Subsequent Event [Member] \| Common Class A [Member]
Subsequent Event [Line Items]
Dividend Declared amount per share	$ 0.10
Subsequent Event [Member] \| Common Class B [Member]
Subsequent Event [Line Items]
Dividend Declared amount per share	$ 0.10