Loans and Leases - Schedule of Credit Quality Indicator, Loan Class and Year of Origination the Amortized Cost Basis of Loans And Leases (Details) $ in Millions	Sep. 30, 2021 USD ($)
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	$ 43,687
Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	39,949
Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	3,738
2021
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	6,847
2021 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	6,196
2021 | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	651
2020
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	10,224
2020 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	9,481
2020 | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	743
2019
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	6,894
2019 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	6,300
2019 | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	594
2018
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	5,562
2018 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	5,463
2018 | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	99
2017
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	3,880
2017 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	3,700
2017 | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	180
Prior to 2017
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	9,005
Prior to 2017 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	8,791
Prior to 2017 | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	214
Revolving Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	1,275
Revolving Loans | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	18
Revolving Loans | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	1,257
Pass | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	37,401
Pass | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	3,681
Pass | 2021 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	6,196
Pass | 2021 | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	651
Pass | 2020 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	9,374
Pass | 2020 | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	741
Pass | 2019 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	5,912
Pass | 2019 | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	592
Pass | 2018 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	4,948
Pass | 2018 | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	98
Pass | 2017
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	3,446
Pass | 2017 | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	172
Pass | Prior to 2017 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	7,508
Pass | Prior to 2017 | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	199
Pass | Revolving Loans | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	17
Pass | Revolving Loans | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	1,228
Special Mention | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	1,784
Special Mention | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	3
Special Mention | 2020 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	90
Special Mention | 2019 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	280
Special Mention | 2018 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	363
Special Mention | 2017 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	143
Special Mention | Prior to 2017 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	908
Special Mention | Revolving Loans | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	3
Substandard | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	764
Substandard | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	54
Substandard | 2020 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	17
Substandard | 2020 | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	2
Substandard | 2019 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	108
Substandard | 2019 | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	2
Substandard | 2018 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	152
Substandard | 2018 | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	1
Substandard | 2017 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	111
Substandard | 2017 | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	8
Substandard | Prior to 2017 | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	375
Substandard | Prior to 2017 | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	15
Substandard | Revolving Loans | Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	1
Substandard | Revolving Loans | Other Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and lease receivable amortized cost basis	$ 26