Changes in Shareholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Dividends declared per share	$ 0.19	$ 0.18
Common Class A [Member]
Dividends declared per share	0.19	0.18
Common Class B [Member]
Dividends declared per share	$ 0.19	$ 0.18
ASC 842 [Member]
Increase decrease in retained earnings		$ 0.1
ASC 326 [Member]
Increase decrease in retained earnings	$ 1.4