Effective Income Tax Rate Reconciliation, Return To Provision, Amount

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- Definition

Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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A brief description of status of the tax examination, significant findings to date, and the entity's position with respect to the findings.

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- Definition

Amount of income tax expense (benefit) from continuing operations attributable to an adjustment of a deferred tax liability or asset for enacted changes in tax laws or rates or a change in the tax status of the entity.

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- Definition

The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

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- Definition

The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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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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Federal Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Provisional tax benefit due to effect of reducing the statutory tax rate	$ 206,400,000	$ 206,400,000	$ 206,400,000
Statutory tax rate		21.00%	35.00%	35.00%
Income taxes paid or refunded, net		$ 22,234,000	$ 33,640,000	$ 33,367,000
Income tax examination description		American National’s federal income tax returns for years 2015 to 2017 are subject to examination by the Internal Revenue Service.
Tax Credit Carryforward [Line Items]
Return to provision		$ 20,301,000	$ 0	$ 0
AMT Credit Carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforward		6,933,000
General Business Tax Credit Carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforward		758,000
Capital Loss Carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforward		$ 656,000