CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (Parentheticals) - $ / shares	3 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Consolidated Statement of Changes in Equity (Parenthetical) [Abstract]
Cash dividends declared and paid, quarterly, per Class A share	$ 0.25	$ 0.25	$ 0.25	$ 0.210	$ 0.210	$ 0.195