Condensed Consolidated Balance Sheets (Parenthetical) - shares	Sep. 30, 2020	Dec. 31, 2019
Common Class A
Common shares issued (in shares)	69,051,284	68,788,257
Common shares outstanding (in shares)	69,051,284	68,788,257
Common Class B
Common shares issued (in shares)	79,233,544	79,233,544
Common shares outstanding (in shares)	79,233,544	79,233,544

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://fasb.org/us-gaap/role/ref/legacyRef
-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=120391452&loc=d3e13212-122682

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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant