Percentage of cumulative preferred stock.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

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

+ References

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- Definition

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

+ References

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- Definition

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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- Definition

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

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- Definition

Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

+ References

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- Definition

The price per share at which the preferred stock of an entity that has priority over common stock in the distribution of dividends and in the event of liquidation of the entity is redeemed or may be called at. The redemption features of this preferred stock are solely within the control of the issuer.

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- Definition

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.

+ References

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- Definition

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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- Definition

Number of treasury shares or units reissued. Excludes reissuance of shares or units in treasury for award under share-based payment arrangement.

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- Definition

Amount of stock repurchase plan authorized.

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No definition available.

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- Definition

Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

+ References

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Number of shares that have been repurchased during the period and are being held in treasury.

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The amount allocated to treasury stock. Treasury stock is common and preferred shares of an entity that were issued, repurchased by the entity, and are held in its treasury.

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Capital Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Capital Unit [Line Items]
Preferred stock, par value (dollars per share)	$ 50,000	$ 50,000
Cumulative preferred nonvoting stock (as a percent)	4.50%	4.50%
Shares held in treasury (in shares)	23,013,489	23,240,197
Preferred stock included in Treasury shares at cost line of the Consolidated Balance Sheet	$ 327,756	$ 305,159
Common stock, shares authorized (in shares)	180,000,000	180,000,000
Common stock, no par value (in dollars per share)	$ 0	$ 0
Common stock, shares issued (in shares)	62,081,391	62,081,391
Common stock, shares outstanding (in shares)	39,067,902	38,841,194
Stock Issued During Period, Shares, Treasury Stock Reissued	471,681	436,549
4 1/2% Cumulative Preferred Nonvoting Stock
Capital Unit [Line Items]
Preferred stock, shares authorized	100,000
Preferred stock, par value (dollars per share)	$ 50
Cumulative preferred nonvoting stock (as a percent)	4.50%
Preferred stock, callable price per share (dollars per share)	$ 52.50
Preferred stock, shares issued	71,340	71,340
Shares held in treasury (in shares)	52,998	52,878
Preferred stock included in Treasury shares at cost line of the Consolidated Balance Sheet	$ 1,800
Treasury purchases (in shares)	120	0
Second Cumulative Preferred Voting Stock
Capital Unit [Line Items]
Preferred stock, shares authorized	1,000,000
Preferred stock, par value (dollars per share)	$ 10
Preferred stock, shares issued	0	0
Common Stock
Capital Unit [Line Items]
Common stock, shares outstanding (in shares)	62,081,391	62,081,391	62,081,391	62,081,391
Treasury
Capital Unit [Line Items]
Common stock, shares outstanding (in shares)	23,013,489	23,240,197	23,554,868	23,858,463
Share Repurchase Program, May 2015 \| Common Stock
Capital Unit [Line Items]
Stock repurchased program, authorized amount (up to)	$ 100,000
Share Repurchase Program, May 2015 \| Treasury
Capital Unit [Line Items]
Treasury purchases (in shares)	175,000	33,465	0