CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical)	6 Months Ended
Jun. 30, 2019 shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	15,000
Common Stock Class A [Member]
Stock Repurchased During Period, Shares	48,551
Common Stock Class D [Member]
Stock Repurchased During Period, Shares	2,126,790
Conversion of Stock, Shares Converted	755,239

Number of share options (or share units) exercised during the current period.

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