Stockholders' Equity - Components and Voting Power of Outstanding Common Stock (Detail) - shares	3 Months Ended
Mar. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Shares Outstanding (in shares)	119,492,089
Percentage	100.00%
Class A Common Stock
Class of Stock [Line Items]
Shares Outstanding (in shares)	52,101,585	30,486,858
Percentage	43.60%
Class B Common Stock
Class of Stock [Line Items]
Shares Outstanding (in shares)	67,390,504	88,942,052
Percentage	56.40%

Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-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 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

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