Condensed Consolidated Balance Sheets (Parenthetical) - shares	Mar. 31, 2018	Dec. 31, 2017	May 15, 2017
Common Class A
Common shares issued (in shares)	64,268,027	62,314,850
Common shares outstanding (in shares)	64,268,027	62,314,850
Common Class B
Common shares issued (in shares)	81,418,003	81,463,433	7,142,857
Common shares outstanding (in shares)	81,418,003	81,463,433

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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

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