Investment Securities - Schedule of unrealized loss on investments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Investment [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 86,393	$ 237,613
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	695	1,106
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	4,727	171,805
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	33	5,117
Debt Securities, Available-for-sale, Unrealized Loss Position	91,120	409,418
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	728	6,223
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Investment [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	86,393	237,613
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	695	1,106
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	4,727	171,805
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	33	5,117
Debt Securities, Available-for-sale, Unrealized Loss Position	91,120	409,418
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 728	$ 6,223

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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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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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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 less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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