Earnings Per Share And Shareholder's Equity (Details) - USD ($)	1 Months Ended	3 Months Ended	12 Months Ended
	Oct. 31, 2015	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Oct. 31, 2018	Oct. 30, 2015
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Period in Force	3 years
Stock repurchase program, authorized amount					$ 1,000,000,000.0	$ 2,000,000,000.0
Average repurchase price (in USD per share)			$ 77.93	$ 71.72
Proceeds from (Repurchase of) Equity			$ (400,000,000.0)	$ (191,500,000)
Common Stock
Equity, Class of Treasury Stock [Line Items]
Repurchases of ordinary shares, shares		0	5,100,000	2,700,000