Stockholders' Equity - Summary of Cash Dividends Declared on Class A Common Stock (Detail) - $ / shares	3 Months Ended
Jun. 30, 2017	Mar. 31, 2017
Equity [Abstract]
Dividends Per Share (in dollars per share)	$ 0.4180	$ 0.4138
Dividends Payable, Date Declared	May 04, 2017	Feb. 24, 2017
Record date for dividends declared	Jun. 30, 2017	Mar. 31, 2017
Dividends payment date	Jul. 31, 2017	Apr. 28, 2017

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-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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The per share amount of a dividend declared, but not paid, as of the financial reporting date.

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

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- Definition

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

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