Investment (Held-to-Maturity) Securities (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2023 USD ($)		Dec. 31, 2022 USD ($)
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Debt Securities, Held-to-maturity, gross		$ 2,409,090		$ 2,739,241
Debt Securities, Held-to-Maturity, carrying value		2,244,489	[1]	2,514,245	[2]
Debt Securities, Held-to-maturity, Allowance for Credit Loss		336	[1]	558	[2]
Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss		2,408,754		2,738,683
Debt Securities, Held-to-Maturity, Carrying Value, after Allowance for Credit Loss		2,244,153	[1]	2,513,687	[2]
Investment Securities, fair value		2,072,586		2,346,768
Investment Securities, Gross Unrealized Gain		5,139		6,611
Investment Securities, Gross Unrealized Loss		(177,042)		(174,088)
Debt Securities, Net Unrealized Loss Remaining in AOCI included in Carrying Value for AFS Securities Transferred to Investment Securities		$ (165,000)		$ (225,000)
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		134		143
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 1,931		$ 2,184,167
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		1,947,071		801
Investment Securities, Continuous Unrealized Loss Position, Fair Value		1,949,002		2,184,968
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Losses		5		174,012
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Losses		177,037		76
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss		177,042		174,088
Fixed maturity securities [Member]
Investment Securities, Debt Maturities, Net, Amortized Cost [Abstract]
Investment Securities, Debt Maturities, Less than One Year, Net Carrying Value		17,262
Investment Securities, Debt Maturities, One to Five Years, Net Carrying Value		108,343
Investment Securities, Debt Maturities, Six to Ten Years, Net Carrying Value		26,788
Investment Securities, Debt Maturities, Over Ten Years, Net Carrying Value		13
Investment Securities, Debt Maturities, Single Maturity Date, Carrying Value		152,406
Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Investment Securities, Debt Maturities, Less than One Year, Fair Value		17,314
Investment Securities, Debt Maturities, One to Five Years, Fair Value		112,140
Investment Securities, Debt Maturities, Six to Ten Years, Fair Value		25,309
Investment Securities, Debt Maturities, Over Ten Years, Fair Value		13
Investment Securities, Debt Maturities, Single Maturity Date, Fair value		$ 154,776
Investment Securities, Debt Maturities, Weighted Average Maturity	[3]	3.29
Municipal securities [Member]
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Debt Securities, Held-to-maturity, gross		$ 120,705		170,629
Debt Securities, Held-to-Maturity, carrying value		120,705	[1]	170,629	[2]
Investment Securities, fair value		125,525		176,621
Investment Securities, Gross Unrealized Gain		5,014		6,456
Investment Securities, Gross Unrealized Loss		$ (194)		$ (464)
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		13		22
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 1,931		$ 18,037
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		6,600		544
Investment Securities, Continuous Unrealized Loss Position, Fair Value		8,531		18,581
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Losses		5		406
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Losses		189		58
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss		194		464
Residential agency mortgage-backed securities [Member]
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Debt Securities, Held-to-maturity, gross		2,255,340		2,538,565
Debt Securities, Held-to-Maturity, carrying value		2,092,083	[1]	2,315,219	[2]
Investment Securities, fair value		1,917,810		2,143,360
Investment Securities, Gross Unrealized Gain		125		155
Investment Securities, Gross Unrealized Loss		(174,398)		$ (172,014)
Investment Securities, Debt Maturities, Net, Amortized Cost [Abstract]
Investment Securities, Debt Maturities, without Single Maturity Date, Net Carrying value	[4]	2,092,083
Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Investment Securities, Debt Maturities, without Single Maturity Date, Fair value		$ 1,917,810
Investment Securities, Debt Maturities, Average Expected Life of Mortgage-backed Securities		5 years
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		116		116
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 0		$ 2,142,114
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		1,916,732		0
Investment Securities, Continuous Unrealized Loss Position, Fair Value		1,916,732		2,142,114
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Losses		0		172,014
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Losses		174,398		0
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss		174,398		172,014
Commercial agency mortgage-backed securities [Member]
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Debt Securities, Held-to-maturity, gross		17,258		17,259
Debt Securities, Held-to-Maturity, carrying value		15,914	[1]	15,609	[2]
Investment Securities, fair value		15,067		14,588
Investment Securities, Gross Unrealized Gain		0		0
Investment Securities, Gross Unrealized Loss		$ (847)		$ (1,021)
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		2		2
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 0		$ 14,588
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		15,067		0
Investment Securities, Continuous Unrealized Loss Position, Fair Value		15,067		14,588
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Losses		0		1,021
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Losses		847		0
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss		847		1,021
Other debt securities [Member]
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Debt Securities, Held-to-maturity, gross		15,787		12,788
Debt Securities, Held-to-Maturity, carrying value		15,787	[1]	12,788	[2]
Investment Securities, fair value		14,184		12,199
Investment Securities, Gross Unrealized Gain		0		0
Investment Securities, Gross Unrealized Loss		$ (1,603)		$ (589)
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		3		3
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 0		$ 9,428
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		8,672		257
Investment Securities, Continuous Unrealized Loss Position, Fair Value		8,672		9,685
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Losses		0		571
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Losses		1,603		18
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ 1,603		$ 589

[1] Carrying value includes $165 million of net unrealized loss which remains in AOCI in the Consolidated Balance Sheets related to certain securities transferred during the second quarter of 2022 from the Available for Sale securities portfolio to the Investment securities portfolio.

[2] Carrying value includes $225 million of net unrealized loss which remains in AOCI in the Consolidated Balance Sheets related to certain securities transferred during the second quarter of 2022 from the Available for Sale securities portfolio to the Investment securities portfolio.

[3] Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without penalty.

[4] The average expected lives of residential mortgage-backed securities were 5.0 years based upon current prepayment assumptions.