Goodwill and Other Intangible Assets - Gross Carrying Amount, Accumulated Amortization And Net Carrying Amount Of Other Intangible Assets (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 4,334	$ 4,430
Accumulated Amortization	(2,179)	(2,061)
Net Carrying Amount	2,155	2,369	$ 1,613
Client relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	3,154	3,262
Accumulated Amortization	(1,683)	(1,605)
Net Carrying Amount	1,471	1,657
Technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	404	389
Accumulated Amortization	(70)	(49)
Net Carrying Amount	334	340
Core deposits
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	675	676
Accumulated Amortization	(366)	(350)
Net Carrying Amount	309	326
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	101	103
Accumulated Amortization	(60)	(57)
Net Carrying Amount	$ 41	$ 46