Consolidated Statements Of Changes In Equity (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Preferred dividends on subsidiaries' preferred stock	$ 13.7	$ 19.1	$ 14.9