Loans and Leases - Quality of Loans Held for Investment (Details) - USD ($) $ in Millions		Sep. 30, 2021		Dec. 31, 2020		Sep. 30, 2020
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Receivable		$ 43,631		$ 42,822
Multi-Family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Receivable		32,838		32,236
Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Receivable		6,715		6,836
One-to-Four Family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Receivable		170		236
Acquisition, Development, and Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Receivable		198		90
Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- Accrual Loans						$ 6
Total Loans Receivable	[2]	3,704	[1]	3,417	[3]
Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans Receivable		6		7
Non-Covered Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		475		54
Non- Accrual Loans		28		38
Current Loans		43,156		42,768
Total Loans Receivable		43,631		42,822
Non-Covered Loans | Financing Receivable, 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		447		16
Non-Covered Loans | Multi-Family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		434		8
Non- Accrual Loans		8		4
Current Loans		32,404		32,228
Total Loans Receivable		32,838		32,236
Non-Covered Loans | Multi-Family | Financing Receivable, 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		426		4
Non-Covered Loans | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		23		22
Non- Accrual Loans		12		12
Current Loans		6,692		6,814
Total Loans Receivable		6,715		6,836
Non-Covered Loans | Commercial Real Estate | Financing Receivable, 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		11		10
Non-Covered Loans | One-to-Four Family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		11		4
Non- Accrual Loans		1		2
Current Loans		159		232
Total Loans Receivable		170		236
Non-Covered Loans | One-to-Four Family | Financing Receivable, 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		10		2
Non-Covered Loans | Acquisition, Development, and Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans		198		90
Total Loans Receivable		198		90
Non-Covered Loans | Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		7	[4],[5]	20	[6],[7]
Non- Accrual Loans		7	[4],[5]	20	[6],[7]
Current Loans		3,697	[4],[5]	3,397	[6],[7]
Total Loans Receivable		3,704	[4],[5]	3,417	[6],[7]
Non-Covered Loans | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans		6		7
Total Loans Receivable		$ 6		$ 7

[1] Includes lease financing receivables, all of which were classified as Pass.

[2] Includes specialty finance loans and leases of $3.1 billion and $3.0 billion, respectively, at September 30, 2021 and December 31, 2020, and other C&I loans of $561 million and $393 million, respectively, at September 30, 2021 and December 31, 2020.

[3] Includes lease financing receivables, all of which were classified as Pass.

[4] Includes $7 million of taxi medallion-related loans that were 90 days or more past due. There were no taxi medallion-related loans that were 30 to 89 days past due.

[5] Includes lease financing receivables, all of which were current.

[6] Includes $19 million of taxi medallion-related loans that were 90 days or more past due. There were no taxi medallion-related loans that were 30 to 89 days past due.

[7] Includes lease financing receivables, all of which were current.