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Debt Securities Available-for-Sale - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021 USD ($) security	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) security	Jun. 30, 2020 USD ($)
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, restricted	$ 557,000		$ 557,000
Debt securities, available-for-sale, realized gain	509	$ 74	606	$ 74
Debt securities, available-for-sale, realized loss	0	1	0	14
Proceeds from sales and calls of debt securities available-for-sale	89,600	12,600	95,472	12,623
Debt securities, trading, realized gain (loss)	807	$ 1,600	1,200	$ (366)
Accrued interest receivable associated with debt securities available-for-sale	$ 1,900		$ 1,900
Real Estate Mortgage Investment Conduits (REMICs) | GSE
Debt Securities, Available-for-sale [Line Items]
Number of debt securities, unrealized loss position less than 12 months | security	1		1
Real Estate Mortgage Investment Conduits (REMICs) | GSE | Pass Through
Debt Securities, Available-for-sale [Line Items]
Number of debt securities, unrealized loss position longer than 12 months | security	9		9
Number of debt securities, unrealized loss position less than 12 months | security	17		17
Real Estate Mortgage Investment Conduits (REMICs) | GSE | Non Pass Through
Debt Securities, Available-for-sale [Line Items]
Number of debt securities, unrealized loss position less than 12 months | security	41		41
Real Estate Mortgage Investment Conduits (REMICs) | Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Number of debt securities, unrealized loss position less than 12 months | security	2		2

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Amount, after allowance for credit loss, of accrued interest 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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Number of investments in debt securities 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 an allowance for credit loss. Includes beneficial interest in securitized financial asset.

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