Business Combinations - Preliminary Allocation (Details) - USD ($) $ in Millions	Mar. 20, 2023	Dec. 01, 2022
Signature Bridge Bank
Business Acquisition [Line Items]
Purchase Price consideration	$ 85
Fair value of assets acquired:
Cash & cash equivalents	24,901
Loans held for sale	232
Loans held for investment:	11,741
CDI and other intangible assets	464
Other assets	413
Total assets acquired	37,751
Fair value of liabilities assumed:
Deposits	33,507
Other liabilities	2,149
Total liabilities assumed	35,656
Fair value of net identifiable assets	2,095
Bargain purchase gain	2,010
Signature Bridge Bank \| As Initially Reported
Business Acquisition [Line Items]
Purchase Price consideration	85
Fair value of assets acquired:
Cash & cash equivalents	25,043
Loans held for sale	232
Loans held for investment:	12,218
CDI and other intangible assets	464
Other assets	679
Total assets acquired	38,636
Fair value of liabilities assumed:
Deposits	33,568
Other liabilities	2,982
Total liabilities assumed	36,550
Fair value of net identifiable assets	2,086
Bargain purchase gain	2,001
Signature Bridge Bank \| Measurement Period Adjustments
Fair value of liabilities assumed:
Bargain purchase gain	2,010
Measurement Period Adjustments
Cash & cash equivalents	(142)
Loans held for investment:	(477)
CDI and other intangible assets	0
Other assets	(266)
Total assets acquired	(885)
Deposits	(61)
Other liabilities	(833)
Total liabilities assumed	(894)
Fair value of net identifiable assets	9
Bargain purchase gain	9
Signature Bridge Bank \| Commercial and industrial
Fair value of assets acquired:
Loans held for investment:	9,888
Signature Bridge Bank \| Commercial and industrial \| As Initially Reported
Fair value of assets acquired:
Loans held for investment:	10,102
Signature Bridge Bank \| Commercial and industrial \| Measurement Period Adjustments
Measurement Period Adjustments
Loans held for investment:	(214)
Signature Bridge Bank \| Commercial real estate
Fair value of assets acquired:
Loans held for investment:	1,680
Signature Bridge Bank \| Commercial real estate \| As Initially Reported
Fair value of assets acquired:
Loans held for investment:	1,942
Signature Bridge Bank \| Commercial real estate \| Measurement Period Adjustments
Measurement Period Adjustments
Loans held for investment:	(262)
Signature Bridge Bank \| Consumer and other
Fair value of assets acquired:
Loans held for investment:	173
Signature Bridge Bank \| Consumer and other \| As Initially Reported
Fair value of assets acquired:
Loans held for investment:	174
Signature Bridge Bank \| Consumer and other \| Measurement Period Adjustments
Measurement Period Adjustments
Loans held for investment:	$ (1)
Flagstar Bancorp
Business Acquisition [Line Items]
Purchase Price consideration		$ 2,010
Fair value of assets acquired:
Cash & cash equivalents		331
Securities		2,695
Loans held for sale		1,257
Loans held for investment:		18,008
CDI and other intangible assets		292
Mortgage servicing rights		1,012
Other assets		2,158
Total assets acquired		25,753
Fair value of liabilities assumed:
Deposits		15,995
Borrowings		6,700
Other liabilities		889
Total liabilities assumed		23,584
Fair value of net identifiable assets		2,169
Bargain purchase gain		159
Flagstar Bancorp \| Commercial and industrial
Fair value of assets acquired:
Loans held for investment:		3,891
Flagstar Bancorp \| Commercial real estate
Fair value of assets acquired:
Loans held for investment:		6,523
Flagstar Bancorp \| Consumer and other
Fair value of assets acquired:
Loans held for investment:		2,156
Flagstar Bancorp \| One-to-four family first mortgage
Fair value of assets acquired:
Loans held for investment:		$ 5,438

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