Acquisitions and Divestitures (Details) $ in Millions	Apr. 01, 2016 USD ($) branch	Sep. 30, 2015 USD ($) branch	Jun. 30, 2015 USD ($) branch	Mar. 31, 2015 USD ($) branch
Susquehanna
Business Acquisition [Line Items]
Total assets acquired		$ 18,300
Additional deposits acquired		$ 14,100
Susquehanna | Pennsylvania, Maryland, New Jersey and West Virginia
Business Acquisition [Line Items]
Number of branches | branch		245
The Bank of Kentucky
Business Acquisition [Line Items]
Total assets acquired			$ 2,000
Additional deposits acquired			$ 1,600
Number of branches | branch			32
Citi 41 Branches in Texas
Business Acquisition [Line Items]
Total assets acquired				$ 238
Additional deposits acquired				$ 1,900
Citi 41 Branches in Texas | Texas
Business Acquisition [Line Items]
Number of branches | branch				41
National Penn Bancshares, Inc. | Subsequent event
Business Acquisition [Line Items]
Total assets acquired	$ 9,600
Additional deposits acquired	$ 6,600
Number of branches | branch	126
Total consideration	$ 1,600
Cash paid for acquisition	550
CGSC North America Holdings Corporation | Subsequent event
Business Acquisition [Line Items]
Cash paid for acquisition	$ 500