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Dividends Declared Per Share (Detail) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Dividends Payable [Line Items]
Dividend Amount	$ 0.370	$ 0.365	$ 1.11	$ 1.095
Group One
Dividends Payable [Line Items]
Declaration Date			Oct. 23, 2019
Date Paid (Payable)			Nov. 27, 2019
Shareholder of Record Date			Nov. 13, 2019
Dividend Amount			$ 0.370
Group Two
Dividends Payable [Line Items]
Declaration Date			Jul. 24, 2019
Date Paid (Payable)			Aug. 29, 2019
Shareholder of Record Date			Aug. 15, 2019
Dividend Amount			$ 0.370
Group Three
Dividends Payable [Line Items]
Declaration Date			Apr. 24, 2019
Date Paid (Payable)			May 29, 2019
Shareholder of Record Date			May 15, 2019
Dividend Amount			$ 0.370
Group Four
Dividends Payable [Line Items]
Declaration Date			Jan. 30, 2019
Date Paid (Payable)			Feb. 28, 2019
Shareholder of Record Date			Feb. 14, 2019
Dividend Amount			$ 0.370
Group Five
Dividends Payable [Line Items]
Declaration Date			Oct. 24, 2018
Date Paid (Payable)			Nov. 29, 2018
Shareholder of Record Date			Nov. 15, 2018
Dividend Amount			$ 0.365
Group Six
Dividends Payable [Line Items]
Declaration Date			Jul. 25, 2018
Date Paid (Payable)			Aug. 29, 2018
Shareholder of Record Date			Aug. 15, 2018
Dividend Amount			$ 0.365
Group Seven
Dividends Payable [Line Items]
Declaration Date			Apr. 25, 2018
Date Paid (Payable)			May 29, 2018
Shareholder of Record Date			May 15, 2018
Dividend Amount			$ 0.365
Group Eight
Dividends Payable [Line Items]
Declaration Date			Jan. 30, 2018
Date Paid (Payable)			Feb. 28, 2018
Shareholder of Record Date			Feb. 14, 2018
Dividend Amount			$ 0.365

X

- Definition

Aggregate dividends declared during the period for each share of common stock outstanding.

+ References

Reference 1: 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)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

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- Definition

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

+ References

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

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
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Date the holder must own the stock to be entitled to the dividend, in CCYY-MM-DD format.

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