Loans and Leases - Loans Held for Investment by Credit Quality Indicator (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Amortized Cost Basis by Closing Year
Total	$ 64,121		$ 64,121		$ 68,272
Year to date gross charge-offs
Total	(140)	$ (354)	(264)	$ (445)
Loans and leases held for investment: | Multi-family
Amortized Cost Basis by Closing Year
Originated year one	0		0		19
Originated year two	18		18		837
Originated year three	852		852		7,929
Originated year four	7,815		7,815		7,776
Originated year five	7,639		7,639		7,649
Prior year	15,467		15,467		9,850
Revolving Loans	10		10		33
Revolving Loans Converted to Term Loans	131		131		0
Total	31,932		31,932		34,093
Year to date gross charge-offs
Originated year one			0		0
Originated year two			0		0
Originated year three			0		(28)
Originated year four			(39)		(34)
Originated year five			(56)		(42)
Prior year			(90)		(204)
Revolving Loans			0		0
Revolving Loans Converted to Term Loans			0		0
Total	(105)	(76)	(185)	(87)	(308)
Loans and leases held for investment: | Multi-family | Pass
Amortized Cost Basis by Closing Year
Originated year one	0		0		17
Originated year two	16		16		700
Originated year three	680		680		6,599
Originated year four	6,702		6,702		6,070
Originated year five	5,773		5,773		5,203
Prior year	9,138		9,138		3,997
Revolving Loans	6		6		27
Revolving Loans Converted to Term Loans	115		115		0
Total	22,430		22,430		22,613
Loans and leases held for investment: | Multi-family | Special Mention
Amortized Cost Basis by Closing Year
Originated year one	0		0		0
Originated year two	0		0		14
Originated year three	24		24		688
Originated year four	382		382		694
Originated year five	581		581		646
Prior year	568		568		795
Revolving Loans	0		0		1
Revolving Loans Converted to Term Loans	0		0		0
Total	1,555		1,555		2,838
Loans and leases held for investment: | Multi-family | Substandard
Amortized Cost Basis by Closing Year
Originated year one	0		0		2
Originated year two	2		2		123
Originated year three	148		148		529
Originated year four	460		460		868
Originated year five	960		960		1,526
Prior year	3,969		3,969		3,834
Revolving Loans	4		4		5
Revolving Loans Converted to Term Loans	16		16		0
Total	5,559		5,559		6,887
Loans and leases held for investment: | Multi-family | Non-accrual
Amortized Cost Basis by Closing Year
Originated year one	0		0		0
Originated year two	0		0		0
Originated year three	0		0		113
Originated year four	271		271		144
Originated year five	325		325		274
Prior year	1,792		1,792		1,224
Revolving Loans	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	2,388		2,388		1,755
Loans and leases held for investment: | Commercial real estate
Amortized Cost Basis by Closing Year
Originated year one	558		558		544
Originated year two	430		430		1,438
Originated year three	1,290		1,290		2,096
Originated year four	1,882		1,882		1,321
Originated year five	1,132		1,132		848
Prior year	3,642		3,642		3,376
Revolving Loans	1,301		1,301		1,840
Revolving Loans Converted to Term Loans	401		401		373
Total	10,636		10,636		11,836
Year to date gross charge-offs
Originated year one			0		0
Originated year two			0		(8)
Originated year three			0		(81)
Originated year four			(1)		(1)
Originated year five			0		(27)
Prior year			(21)		(349)
Revolving Loans			0		0
Revolving Loans Converted to Term Loans			0		0
Total	(20)	(237)	(22)	(301)	(466)
Loans and leases held for investment: | Commercial real estate | Pass
Amortized Cost Basis by Closing Year
Originated year one	558		558		542
Originated year two	423		423		1,298
Originated year three	1,101		1,101		1,753
Originated year four	1,531		1,531		1,106
Originated year five	1,011		1,011		576
Prior year	2,394		2,394		2,068
Revolving Loans	1,115		1,115		1,597
Revolving Loans Converted to Term Loans	171		171		367
Total	8,304		8,304		9,307
Loans and leases held for investment: | Commercial real estate | Special Mention
Amortized Cost Basis by Closing Year
Originated year one	0		0		0
Originated year two	3		3		72
Originated year three	82		82		130
Originated year four	113		113		69
Originated year five	11		11		106
Prior year	96		96		138
Revolving Loans	47		47		120
Revolving Loans Converted to Term Loans	58		58		0
Total	410		410		635
Loans and leases held for investment: | Commercial real estate | Substandard
Amortized Cost Basis by Closing Year
Originated year one	0		0		2
Originated year two	4		4		31
Originated year three	68		68		179
Originated year four	207		207		110
Originated year five	85		85		162
Prior year	688		688		723
Revolving Loans	137		137		117
Revolving Loans Converted to Term Loans	170		170		6
Total	1,359		1,359		1,330
Loans and leases held for investment: | Commercial real estate | Non-accrual
Amortized Cost Basis by Closing Year
Originated year one	0		0		0
Originated year two	0		0		37
Originated year three	39		39		34
Originated year four	31		31		36
Originated year five	25		25		4
Prior year	464		464		447
Revolving Loans	2		2		6
Revolving Loans Converted to Term Loans	2		2		0
Total	563		563		564
Loans and leases held for investment: | One-to-four family first mortgage
Amortized Cost Basis by Closing Year
Originated year one	315		315		251
Originated year two	340		340		527
Originated year three	488		488		2,455
Originated year four	2,358		2,358		871
Originated year five	841		841		201
Prior year	1,017		1,017		809
Revolving Loans	83		83		85
Revolving Loans Converted to Term Loans	3		3		2
Total	5,445		5,445		5,201
Year to date gross charge-offs
Originated year one			0		0
Originated year two			0		0
Originated year three			0		(1)
Originated year four			(1)		0
Originated year five			0		0
Prior year			(1)		(7)
Revolving Loans			0		0
Revolving Loans Converted to Term Loans			0		0
Total	(1)	(1)	(2)	(1)	(8)
Loans and leases held for investment: | One-to-four family first mortgage | Pass
Amortized Cost Basis by Closing Year
Originated year one	315		315		250
Originated year two	335		335		521
Originated year three	478		478		2,431
Originated year four	2,326		2,326		859
Originated year five	826		826		178
Prior year	787		787		609
Revolving Loans	81		81		80
Revolving Loans Converted to Term Loans	3		3		2
Total	5,151		5,151		4,930
Loans and leases held for investment: | One-to-four family first mortgage | Special Mention
Amortized Cost Basis by Closing Year
Originated year one					0
Originated year two					0
Originated year three					0
Originated year four					0
Originated year five					0
Prior year					0
Revolving Loans					0
Revolving Loans Converted to Term Loans					0
Total					0
Loans and leases held for investment: | One-to-four family first mortgage | Substandard
Amortized Cost Basis by Closing Year
Originated year one	0		0		1
Originated year two	1		1		2
Originated year three	3		3		8
Originated year four	12		12		2
Originated year five	2		2		16
Prior year	195		195		172
Revolving Loans	0		0		0
Revolving Loans Converted to Term Loans	0		0		0
Total	213		213		201
Loans and leases held for investment: | One-to-four family first mortgage | Non-accrual
Amortized Cost Basis by Closing Year
Originated year one	0		0		0
Originated year two	4		4		4
Originated year three	7		7		16
Originated year four	20		20		10
Originated year five	13		13		7
Prior year	35		35		28
Revolving Loans	2		2		5
Revolving Loans Converted to Term Loans	0		0		0
Total	81		81		70
Loans and leases held for investment: | Commercial and Industrial
Amortized Cost Basis by Closing Year
Originated year one	972		972		1,300
Originated year two	1,171		1,171		2,693
Originated year three	2,480		2,480		2,264
Originated year four	2,188		2,188		736
Originated year five	754		754		467
Prior year	1,113		1,113		798
Revolving Loans	5,412		5,412		5,940
Revolving Loans Converted to Term Loans	336		336		1,178
Total	14,426		14,426		15,376
Year to date gross charge-offs
Originated year one			(9)		(3)
Originated year two			(1)		(20)
Originated year three			(12)		(40)
Originated year four			(15)		(20)
Originated year five			(3)		(19)
Prior year			(1)		(34)
Revolving Loans			0		0
Revolving Loans Converted to Term Loans			0		0
Total			(41)		(136)
Loans and leases held for investment: | Commercial and Industrial | Pass
Amortized Cost Basis by Closing Year
Originated year one	972		972		1,267
Originated year two	1,133		1,133		2,609
Originated year three	2,363		2,363		2,014
Originated year four	1,974		1,974		651
Originated year five	695		695		450
Prior year	1,055		1,055		759
Revolving Loans	5,030		5,030		5,554
Revolving Loans Converted to Term Loans	322		322		1,164
Total	13,544		13,544		14,468
Loans and leases held for investment: | Commercial and Industrial | Special Mention
Amortized Cost Basis by Closing Year
Originated year one	0		0		17
Originated year two	14		14		29
Originated year three	23		23		18
Originated year four	118		118		4
Originated year five	8		8		2
Prior year	4		4		11
Revolving Loans	122		122		119
Revolving Loans Converted to Term Loans	0		0		6
Total	289		289		206
Loans and leases held for investment: | Commercial and Industrial | Substandard
Amortized Cost Basis by Closing Year
Originated year one	0		0		13
Originated year two	20		20		50
Originated year three	66		66		72
Originated year four	47		47		72
Originated year five	42		42		7
Prior year	41		41		13
Revolving Loans	241		241		265
Revolving Loans Converted to Term Loans	13		13		8
Total	470		470		500
Loans and leases held for investment: | Commercial and Industrial | Non-accrual
Amortized Cost Basis by Closing Year
Originated year one	0		0		3
Originated year two	4		4		5
Originated year three	28		28		160
Originated year four	49		49		9
Originated year five	9		9		8
Prior year	13		13		15
Revolving Loans	19		19		2
Revolving Loans Converted to Term Loans	1		1		0
Total	123		123		202
Other loans held for investment
Year to date gross charge-offs
Total	(7)	(5)	(14)	(10)
Other loans held for investment | Commercial and Industrial
Amortized Cost Basis by Closing Year
Total	14,426		14,426		15,376
Year to date gross charge-offs
Total	(7)	$ (35)	(41)	$ (46)
Other loans held for investment | Other
Amortized Cost Basis by Closing Year
Originated year one	36		36		100
Originated year two	27		27		29
Originated year three	28		28		12
Originated year four	12		12		4
Originated year five	4		4		2
Prior year	35		35		37
Revolving Loans	1,439		1,439		1,461
Revolving Loans Converted to Term Loans	101		101		121
Total	1,682		1,682		1,766
Year to date gross charge-offs
Originated year one			(3)		(2)
Originated year two			(1)		(4)
Originated year three			(2)		(4)
Originated year four			(4)		(1)
Originated year five			0		(1)
Prior year			(4)		(8)
Revolving Loans			0		0
Revolving Loans Converted to Term Loans			0		0
Total			(14)		(20)
Other loans held for investment | Other | Pass
Amortized Cost Basis by Closing Year
Originated year one	36		36		100
Originated year two	27		27		29
Originated year three	26		26		12
Originated year four	12		12		4
Originated year five	4		4		2
Prior year	34		34		32
Revolving Loans	1,413		1,413		1,441
Revolving Loans Converted to Term Loans	101		101		121
Total	1,653		1,653		1,741
Other loans held for investment | Other | Special Mention
Amortized Cost Basis by Closing Year
Originated year one	0		0		0
Originated year two	0		0		0
Originated year three	0		0		0
Originated year four	0		0		0
Originated year five	0		0		0
Prior year	0		0		0
Revolving Loans	0		0		1
Revolving Loans Converted to Term Loans	0		0		0
Total	0		0		1
Other loans held for investment | Other | Substandard
Amortized Cost Basis by Closing Year
Originated year one	0		0		0
Originated year two	0		0		0
Originated year three	2		2		0
Originated year four	0		0		0
Originated year five	0		0		0
Prior year	0		0		0
Revolving Loans	2		2		0
Revolving Loans Converted to Term Loans	0		0		0
Total	4		4		0
Other loans held for investment | Other | Non-accrual
Amortized Cost Basis by Closing Year
Originated year one	0		0		0
Originated year two	0		0		0
Originated year three	0		0		0
Originated year four	0		0		0
Originated year five	0		0		0
Prior year	1		1		5
Revolving Loans	24		24		19
Revolving Loans Converted to Term Loans	0		0		0
Total	$ 25		$ 25		$ 24