Exercise price of restricted shares granted.

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Percentage of the the authorized risk based capital requiring actions from either the entity or insurance regulators.

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Term of restrictions on stock.

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Aggregate dividends paid during the period for each share of common stock outstanding.

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Face amount or stated value per share of common stock.

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For insurance companies, a description of the minimum regulatory capital requirements imposed by state insurance regulators, and restrictions on dividend payments.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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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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The highest quantity of shares an employee can purchase under the plan per period.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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Description of significant modifications (such as a change in expiration dating, vesting rights, or exercise prices) to an equity-based compensation plan, including the terms of the modifications.

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Percentage of vesting of share-based compensation awards.

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The amount of statutory capital and surplus (stockholders' equity) as of the balance sheet date using prescribed or permitted statutory accounting practices (rather than GAAP, if different) of the state or country.

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Stockholders' Equity and Noncontrolling Interests - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, par value (in usd per share)	$ 1.00		$ 1.00
Common stock, shares authorized (in shares)	50,000,000		50,000,000
Maximum limit of shares available for grants under stock-based compensation plan	2,900,000
Maximum limit of shares granted to any one individual in any calendar year	200,000
Risk based capital action level percentage	200.00%
Cash dividends to common stockholders (in usd per share)	$ 0.82	$ 0.82	$ 820.00
Description of regulatory capital requirement	American National Insurance Company’s payment of dividends to stockholders is restricted by insurance law. The restrictions require life insurance companies to maintain minimum amounts of capital and surplus, and in the absence of special approval, limit the payment of dividends to the greater of the prior year’s statutory net income from operations, or 10% of prior year statutory surplus.
Noncontrolling interest	$ 12,501,000		$ 14,267,000
Scenario, Forecast
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Statutory amount available for dividend payments without regulatory approval				$ 316,281,000
Parent Company
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Statutory capital and surplus	3,348,300,000		3,162,808,000
Subsidiaries
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Noncontrolling interest	$ 5,751,000		$ 7,517,000
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk based capital action level percentage	200.00%		200.00%
Insurance Subsidiary \| Missouri
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Statutory accounting practices permitted practice amount	$ 70,283,000		$ 69,787,000
County Mutual
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Noncontrolling interest	$ 6,750,000		$ 6,750,000
Stock Appreciation Rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	5 years
Expiration of vesting period	5 years
Stock Appreciation Rights \| Share-based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate per year	20.00%
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	10 years
Lapse restrictions on restricted stock awards	10 years
Shares granted	350,334
Exercise price of Restricted shares granted	$ 0
Number of shares unvested	10,000
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period description	RSUs granted vest after a one-year or three-year graded vesting requirement or over a shorter period as a result of death, disability or retirement after age 65.
Graded Vesting \| Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year