Earnings per Share ("EPS") - Additional Information (Detail) - Class A Common Stock [Member] - shares	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Number of Stock options outstanding	0	0
Minimum [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Class A common stock entitled dividend per share percent in comparison to Class B common stock	200.00%

Number of options outstanding, including both vested and non-vested options.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant