CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)	Jun. 30, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Bonds available-for-sale, pledged as collateral	$ 23,874,000	$ 0
Available-for-sale Securities Pledged as Collateral	23,874,000	0
Investments in partnerships, used as collateral	365,064,000	296,855,000
Loans to a related party	0	53,600,000
Other assets pledged as collateral	$ 17,235,000	$ 0
Preferred shares, no par value	$ 0	$ 0
Preferred shares, shares authorized	5,000,000	5,000,000
Preferred shares, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0	$ 0
Common stock, authorized	50,000,000	50,000,000
Common shares, shares issued (in shares)	(5,704,314)	5,701,946
Common shares, shares outstanding (in shares)	5,704,314	5,701,946
Common shares, non-employee directors' and employee deferred shares (in shares)	106,882	103,069

Number of common shares restricted.

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Face amount per share of no-par value common stock.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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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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For an unclassified balance sheet, reflects the carrying amount of unpaid loan amounts due from related parties at the balance sheet date.

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The carrying amount, as of the date of the latest financial statement presented, of other assets which are owned but transferred to serve as collateral for the payment of the related debt obligation, primarily a secured borrowing or repurchase agreement, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

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The fair value, as of the date of each statement of financial position presented, of other assets which are owned but transferred to serve as collateral for the payment of the related debt obligation, and that are reclassified and separately reported in the statement of financial position because the transferee has the right by contract or custom to sell or re-pledge them.

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Face amount per share of no-par value preferred stock nonredeemable or redeemable solely at the option of the issuer.

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

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Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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