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Investment Securities Available for Sale (Summary of Available for Sale Investment Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 11,013,917	$ 10,991,506
Gross Unrealized Gains	686	66,427
Gross Unrealized Losses	(1,124,753)	(139,604)
Fair Value	9,889,850	10,918,329
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	414,744	120,465
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(28,160)	(2,627)
Fair Value	386,584	117,838
U.S. Government agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	52,866	53,214
Gross Unrealized Gains	2	1,374
Gross Unrealized Losses	(1,973)	(387)
Fair Value	50,895	54,201
Mortgage-backed securities issued by U.S. Government agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	713,490	790,329
Gross Unrealized Gains	6	768
Gross Unrealized Losses	(81,525)	(11,464)
Fair Value	631,971	779,633
Mortgage-backed securities issued by U.S. Government sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	8,144,078	8,063,890
Gross Unrealized Gains	557	50,491
Gross Unrealized Losses	(901,994)	(102,080)
Fair Value	7,242,641	8,012,301
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	826,579	951,691
Gross Unrealized Gains	0	4,658
Gross Unrealized Losses	(73,493)	(16,726)
Fair Value	753,086	939,623
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	642,436	479,420
Gross Unrealized Gains	121	8,644
Gross Unrealized Losses	(37,438)	(6,320)
Fair Value	605,119	481,744
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	201,366	514,188
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	201,366	514,188
Corporate debt securities and other debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	18,358	18,309
Gross Unrealized Gains	0	492
Gross Unrealized Losses	(170)	0
Fair Value	$ 18,188	$ 18,801

X

- Definition

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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