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Investment Securities Available for Sale - Summary Of Available For Sale Investment Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 10,991,506	$ 7,801,864
Gross Unrealized Gains	66,427	177,243
Gross Unrealized Losses	(139,604)	(16,669)
Fair Value	10,918,329	7,962,438
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	120,465	20,257
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(2,627)	0
Fair Value	117,838	20,257
U.S. Government agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	53,214	79,638
Gross Unrealized Gains	1,374	2,682
Gross Unrealized Losses	(387)	0
Fair Value	54,201	82,320
Mortgage-backed securities issued by U.S. Government agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	790,329	1,216,012
Gross Unrealized Gains	768	7,930
Gross Unrealized Losses	(11,464)	(5,925)
Fair Value	779,633	1,218,017
Mortgage-backed securities issued by U.S. Government sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	8,063,890	4,865,858
Gross Unrealized Gains	50,491	134,188
Gross Unrealized Losses	(102,080)	0
Fair Value	8,012,301	5,000,046
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	951,691	1,245,644
Gross Unrealized Gains	4,658	15,309
Gross Unrealized Losses	(16,726)	(10,576)
Fair Value	939,623	1,250,377
Commercial mortgage-backed securities issued by U.S. Government agencies or sponsored enterprises
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	479,420	354,244
Gross Unrealized Gains	8,644	16,677
Gross Unrealized Losses	(6,320)	0
Fair Value	481,744	370,921
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	514,188
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Fair Value	514,188
Corporate debt securities and other debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	18,309	20,211
Gross Unrealized Gains	492	457
Gross Unrealized Losses	0	(168)
Fair Value	$ 18,801	$ 20,500

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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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