Investment Securities Available-for-Sale - Gross unrealized losses and fair value (Details) $ in Thousands	Dec. 31, 2021 USD ($) security	Dec. 31, 2020 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Number of Securities \| security	239	66
Less than 12 months, estimated fair value	$ 1,891,310	$ 222,354
Less than 12 months, unrealized losses	24,285	857
12 months or greater, estimated fair value	177,038	47,739
12 months or greater, unrealized losses	5,322	611
Estimated Fair Value	2,068,348	270,093
Unrealized Losses	$ 29,607	$ 1,468
U.S. Treasury Bond
Debt Securities, Available-for-sale [Line Items]
Number of Securities \| security	1
Less than 12 months, estimated fair value	$ 24,593
Less than 12 months, unrealized losses	257
12 months or greater, estimated fair value	0
12 months or greater, unrealized losses	0
Estimated Fair Value	24,593
Unrealized Losses	$ 257
U.S. agency securities
Debt Securities, Available-for-sale [Line Items]
Number of Securities \| security	64	28
Less than 12 months, estimated fair value	$ 452,966	$ 46,412
Less than 12 months, unrealized losses	6,256	67
12 months or greater, estimated fair value	68,977	41,320
12 months or greater, unrealized losses	1,366	560
Estimated Fair Value	521,943	87,732
Unrealized Losses	$ 7,622	$ 627
Residential mortgage backed securities
Debt Securities, Available-for-sale [Line Items]
Number of Securities \| security	153	35
Less than 12 months, estimated fair value	$ 1,327,519	$ 170,178
Less than 12 months, unrealized losses	16,841	782
12 months or greater, estimated fair value	108,061	6,419
12 months or greater, unrealized losses	3,956	51
Estimated Fair Value	1,435,580	176,597
Unrealized Losses	$ 20,797	$ 833
Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Number of Securities \| security	8	3
Less than 12 months, estimated fair value	$ 20,181	$ 5,764
Less than 12 months, unrealized losses	347	8
12 months or greater, estimated fair value	0	0
12 months or greater, unrealized losses	0	0
Estimated Fair Value	20,181	5,764
Unrealized Losses	$ 347	$ 8
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Number of Securities \| security	13
Less than 12 months, estimated fair value	$ 66,051
Less than 12 months, unrealized losses	584
12 months or greater, estimated fair value	0
12 months or greater, unrealized losses	0
Estimated Fair Value	66,051
Unrealized Losses	$ 584

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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