Shareholders' Equity (Narrative) (Details) - USD ($)						1 Months Ended							3 Months Ended		9 Months Ended		38 Months Ended
	Oct. 23, 2019	Oct. 08, 2018	Aug. 02, 2018	Oct. 30, 2017	Jul. 29, 2016	Nov. 30, 2019	Aug. 31, 2019	Jul. 31, 2019	May 31, 2019	Apr. 30, 2019	Mar. 31, 2019	Feb. 28, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Jul. 31, 2018
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program, repurchased cost													$ 33,100,000	$ 121,100,000	$ 81,200,000	$ 226,100,000
Quarterly dividends declared								$ 0.175		$ 0.175		$ 0.175
Dividends declared							$ 0.175		$ 0.175		$ 0.175		$ 0.175		$ 0.525
Dividends payable, date to be paid, year and month							2019-08		2019-05		2019-03
Subsequent Event [Member]
Equity Class Of Treasury Stock [Line Items]
Quarterly dividends declared	$ 0.20
Scenario Forecast [Member]
Equity Class Of Treasury Stock [Line Items]
Dividends declared						$ 0.20
Dividends payable, date to be paid, year and month						2019-11
Accelerated Share Repurchase [Member] | Deutsche Bank AG [Member]
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program, expiration date															Oct. 08, 2018
Pre payment of repurchase program			$ 150,000,000.0
Repurchase program, Shares			1,766,004
Accelerated share repurchase remaining shares returned		389,825
Common Stock
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program, expiration date					Jul. 31, 2018
Stock repurchase program, additional authorized amount				$ 250,000,000.0														$ 300,000,000.0
Shares repurchase program, extended expiration date				Oct. 31, 2020
Shares repurchase program, shares repurchased													347,304	1,781,917	994,995	3,567,733
Common Stock | Share Repurchase Program Excluding ASR [Member]
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program, shares repurchased													300,000		1,000,000.0
Shares repurchase program, repurchased cost													$ 33,100,000		$ 81,200,000
Shares repurchase program, average price per share													$ 95.26		$ 81.58
Common Stock | Share Repurchase Program Including ASR [Member]
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program, shares repurchased																	8,700,000
Shares repurchase program, repurchased cost																	$ 511,800,000
Shares repurchase program, average price per share																	$ 58.94
Common Stock | Maximum [Member]
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program, authorized amount					$ 150,000,000.0													$ 700,000,000.0