Investment (Held-to-Maturity) Securities (Details) $ in Thousands		3 Months Ended
		Jun. 30, 2022 USD ($)		Dec. 31, 2021 USD ($)
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Investment Securities, Gross Amortized Cost		$ 2,903,116		$ 210,999
Investment Securities, Gross Carrying Value		2,638,062	[1]	210,999
Investment securities, Allowance for Credit Loss		(717)	[1]	(555)
Investment Securities, Amortized Cost, After Allowance for Credit Loss		2,902,399		210,444
Investment Securities, Carrying Value, after Allowance for Credit Loss		2,637,345	[1]	210,444
Investment Securities, Fair Value		2,607,757		231,395
Investment Securities, Gross Unrealized Gain		6,091		20,412
Investment Securities, Gross Unrealized Loss		(36,396)		$ (16)
Debt Securities, Net Unrealized Loss Remaining in AOCI included in Carrying Value for AFS Securities Transferred to Investment Securities		265,000
Transfer of available for sale securities to investment securities		2,400,000
Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Transfer, Amount		2,700,000
Debt Securities, Held-to-maturity, Transfer, Unrealized Gain (Loss)		$ 268,000
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		175		3
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 2,451,661		$ 273
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		550		587
Investment Securities, Continuous Unrealized Loss Position, Fair Value		2,452,211		860
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		36,319		2
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		77		14
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss		36,396		16
Fixed Maturity Securities [Member]
Investment Securities, Debt Maturities, Net Carrying Value [Abstract]
Investment Securities, Debt Maturities, Less than One Year, Net Carrying Value		14,890
Investment Securities, Debt Maturities, One to Five Years, Net Carrying Value		105,177
Investment Securities, Debt Maturities, Six to Ten Years, Net Carrying Value		67,111
Investment Securities, Debt Maturities, Over Ten Years, Net Carrying Value		5,039
Investment Securities, Debt Maturities, Single Maturity Date, Net Carrying Value		192,217
Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Investment Securities, Debt Maturities, Less Than One Year, Fair Value		15,018
Investment Securities, Debt Maturities, One to Five Years, Fair Value		110,157
Investment Securities, Debt Maturities, Six to Ten Years, Fair Value		66,625
Investment Securities, Debt Maturities, Over Ten Years, Fair Value		5,031
Investment Securities, Debt Maturities, Single Maturity Date, Fair Value		$ 196,831
Investment Securities, Debt Maturities, Weighted Average Maturity	[2]	4.49
Municipal securities [Member]
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Investment Securities, Gross Amortized Cost		$ 175,974		203,772
Investment Securities, Gross Carrying Value		175,974	[1]	203,772
Investment Securities, Fair Value		180,783		223,609
Investment Securities, Gross Unrealized Gain		5,819		19,851
Investment Securities, Gross Unrealized Loss		$ (1,010)		$ (14)
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		56		1
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 27,968		$ 0
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		527		587
Investment Securities, Continuous Unrealized Loss Position, Fair Value		28,495		587
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		935		0
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		75		14
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss		1,010		14
Residential agency mortgage-backed securities [Member]
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Investment Securities, Gross Amortized Cost		2,709,094		6,939
Investment Securities, Gross Carrying Value		2,445,845	[1]	6,939
Investment Securities, Fair Value		2,410,926		7,500
Investment Securities, Gross Unrealized Gain		272		561
Investment Securities, Gross Unrealized Loss		(35,191)		0
Investment Securities, Debt Maturities, Net Carrying Value [Abstract]
Investment Securities, Debt Maturities, without Single Maturity Date, Net Carrying Value	[3]	2,445,845
Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Investment Securities, Debt Maturities, without Single Maturity Date, Fair Value		$ 2,410,926
Investment Securities, Debt Maturities, Average Expected Life of Mortgage-backed Securities		5 years 4 months 24 days
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		115
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 2,408,180
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0
Investment Securities, Continuous Unrealized Loss Position, Fair Value		2,408,180
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		35,191
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss		35,191
Other debt securities [Member]
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Investment Securities, Gross Amortized Cost		788		288
Investment Securities, Gross Carrying Value		788	[1]	288
Investment Securities, Fair Value		769		286
Investment Securities, Gross Unrealized Gain		0		0
Investment Securities, Gross Unrealized Loss		$ (19)		$ (2)
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		$ 234		$ 273
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		23		0
Investment Securities, Continuous Unrealized Loss Position, Fair Value		257		273
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		17		2
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		2		0
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss		19		$ 2
Commercial agency mortgage-backed securities [Member]
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Investment Securities, Gross Amortized Cost		17,260
Investment Securities, Gross Carrying Value	[1]	15,455
Investment Securities, Fair Value		15,279
Investment Securities, Gross Unrealized Gain		0
Investment Securities, Gross Unrealized Loss		$ (176)
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		2
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 15,279
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0
Investment Securities, Continuous Unrealized Loss Position, Fair Value		15,279
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		176
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ 176

[1] Carrying value includes $265 million of net unrealized loss which remains in Accumulated other comprehensive income ("AOCI") in the Consolidated Balance Sheets related to certain securities transferred from the Available for Sale securities portfolio to the Investment securities portfolio as discussed in greater detail following.

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

[3] The average expected lives of residential mortgage-backed securities were 5.4 years based upon current prepayment assumptions.