Shareholders' Equity and Noncontrolling Interests, Stock Repurchase (Details) - USD ($) $ in Millions			1 Months Ended	3 Months Ended			6 Months Ended	9 Months Ended		14 Months Ended
	Apr. 24, 2018	Jan. 24, 2017	Oct. 22, 2019	Sep. 30, 2019	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Mar. 31, 2018
Shareholders' Equity
Treasury stock retired (in dollars)				$ 0.0	$ 0.0			$ 0.0	$ 0.0
Payments for shares repurchased and retained in treasury stock (in dollars)				$ 150.0	$ 34.8			$ 558.7	$ 680.2
2018 Stock Repurchase Program and 2017 Stock Repurchase Program
Shareholders' Equity
Number of shares repurchased and retired									7,700,000
Payments for shares repurchased and retired (in dollars)									$ 680.2
2018 Stock Repurchase Program
Shareholders' Equity
Value of shares authorized to be repurchased (in dollars)	$ 2,000.0
Repurchase of stock program, period	3 years
Number of shares repurchased				1,700,000				6,100,000
Payments for shares repurchased (in dollars)				$ 150.0				$ 558.7
Number of treasury shares retired								5,100,000
Treasury stock retired (in dollars)								$ 471.1
Number of shares repurchased and retained in treasury stock								1,000,000.0
Payments for shares repurchased and retained in treasury stock (in dollars)								$ 87.6
Number of shares repurchased and retired							3,500,000
Payments for shares repurchased and retired (in dollars)							$ 298.2
2017 Stock Repurchase Program
Shareholders' Equity
Value of shares authorized to be repurchased (in dollars)		$ 1,000.0
Repurchase of stock program, period		2 years
Number of shares repurchased and retired						4,200,000				12,600,000
Payments for shares repurchased and retired (in dollars)						$ 382.0				$ 1,000.0
Subsequent Event | 2018 Stock Repurchase Program
Shareholders' Equity
Number of shares repurchased and retired			0
Value of shares remaining that may be repurchased under the stock repurchase program (in dollars)			$ 888.1