Represents the number of originators that the company has invested over 10 % of its stockholders equity.

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Represents the percent of insured loans used as base for loans guaranteed by US Department of Education.

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Reflects percentage of outstanding principal amount of loans guaranteed by US Department of Education.

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Represents the percentage of total added credit enhancement in the form of overcollaterization and/or subordination of outstanding principal

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Interest, dividends, rents, ancillary and other revenues earned but not yet received by the entity on its investments.

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Investments in notes or bonds that are collateralized by a specific group of underlying assets owned by the issuer of the notes or bonds which are short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Amount of assets pledged to secure a debt instrument.

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Amount of restricted 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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The cash outflow to acquire debt and equity securities not classified as either held-to-maturity securities or trading securities which would be classified as available-for-sale securities and reported at fair value, with unrealized gains and losses excluded from earnings and reported in a separate component of shareholders' equity.

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The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities.

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Securities - Amortized Cost and Fair Value (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) item	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Securities Available-for-Sale
Amortized Cost		$ 428,439		$ 475,146
Gross Unrealized Gains		23,365		13,285
Gross Unrealized Losses		(3,383)		(3,783)
Fair Value		448,421		484,648
Accrued interest receivable		2,600		3,200
Other disclosures
Purchases		14,681	$ 136,096
Sales	$ 57,228	$ 18,006	$ 177,824
Number of originators \| item		1
Securities pledged to secure deposits and for other purposes		$ 353,200		320,800
US Treasury Securities [Member]
Securities Available-for-Sale
Amortized Cost		4,013		4,010
Gross Unrealized Gains		121		26
Fair Value		4,134		4,036
US Government Corporations and Agencies Securities [Member]
Securities Available-for-Sale
Amortized Cost		7,169		8,502
Gross Unrealized Losses		(164)		(165)
Fair Value		7,005		8,337
U.S. government agencies mortgage-backed
Securities Available-for-Sale
Amortized Cost				16,164
Gross Unrealized Gains				443
Gross Unrealized Losses				(19)
Fair Value				16,588
US States and Political Subdivisions Debt Securities [Member]
Securities Available-for-Sale
Amortized Cost		232,416		240,399
Gross Unrealized Gains		18,316		11,207
Gross Unrealized Losses		(955)		(2,431)
Fair Value		249,777		249,175
Collateralized Mortgage Obligations [Member]
Securities Available-for-Sale
Amortized Cost		54,597		57,059
Gross Unrealized Gains		2,839		963
Gross Unrealized Losses		(423)		(38)
Fair Value		57,013		57,984
Asset-backed Securities [Member]
Securities Available-for-Sale
Amortized Cost		81,986		82,114
Gross Unrealized Gains		905		617
Gross Unrealized Losses		(1,306)		(887)
Fair Value		81,585		81,844
FFEL
Other disclosures
Asset-backed securities		$ 55,900
Percentage of outstanding principal amount of loans guaranteed by US Department of Education		97
Total added credit enhancement in the form of overcollaterization and/or subordination of outstanding principal		$ 5,100
Percentage of total added credit enhancement in the form of overcollaterization and/or subordination of outstanding principal		9.00
FFEL \| Reimbursement requests greater than 5 %
Other disclosures
Percentage of outstanding principal amount of loans guaranteed by US Department of Education		85
Percent of insured loan		5
FFEL \| Reimbursement requests greater than 9 %
Other disclosures
Percentage of outstanding principal amount of loans guaranteed by US Department of Education		75
Percent of insured loan		9
Collateralized loan obligations
Securities Available-for-Sale
Amortized Cost		$ 31,202		66,898
Gross Unrealized Gains		19		29
Gross Unrealized Losses		(533)		(243)
Fair Value		30,688		$ 66,684
Mortgage Backed Securities, Issued by US Government Agencies [Member]
Securities Available-for-Sale
Amortized Cost		17,056
Gross Unrealized Gains		1,165
Gross Unrealized Losses		(2)
Fair Value		18,219
Towd Point Mortgage Trust
Securities Available-for-Sale
Amortized Cost		33,242
Fair Value		$ 35,477
Stockholders' Equity, Total [Member] \| GCO Education Loan Funding Corp [Member]
Other disclosures
Credit risk as a percentage of benchmark		10.00%