Basis of Presentation (Narrative) (Details)				3 Months Ended
	Jan. 01, 2023 $ / shares shares	Aug. 23, 2007 USD ($)	Jun. 21, 2005 USD ($)	Mar. 31, 2023 USD ($) $ / shares shares	May 05, 2023 USD ($)	May 04, 2023 USD ($)	Dec. 31, 2022 USD ($) $ / shares shares
Variable Interest Entity [Line Items]
Receivable from reinsurer				$ 3,953,000			$ 58,882,000
Reinsurance recoverable, allowance for credit loss				200,000
Senior unsecured notes due 2029, carrying value				49,377,000			$ 49,352,000
Deferred tax, valuation allowance				39,000,000.0
Uncertain tax positions				$ 0
Reverse stock split ratio	0.1
Common stock, par value | $ / shares	$ 1.00			$ 1.00			$ 1.00
Common stock, authorized shares | shares	3,333,333			3,333,333			3,333,333
Fractional shares issued (in shares) | shares	0
AM Best, A- Rating [Member]
Variable Interest Entity [Line Items]
Percentage of reinsurance recoverable				96.00%
AM Best, B++ Rating [Member]
Variable Interest Entity [Line Items]
Percentage of reinsurance recoverable				1.00%
AM Best, B+ Rating [Member]
Variable Interest Entity [Line Items]
Percentage of reinsurance recoverable				3.00%
Loss Portfolio Transfer Contract Right Dispute [Member] | Pending Litigation [Member]
Variable Interest Entity [Line Items]
Write off of receivable				$ 32,900,000
Receivable from reinsurer				4,000,000.0
Accounting Standards Update 2016-13 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Variable Interest Entity [Line Items]
Reinsurance recoverable, allowance for credit loss				200,000
Hallmark Statutory Trust I [Member]
Variable Interest Entity [Line Items]
Proceeds from issuance of trust preferred securities			$ 30,000,000.0
Hallmark Statutory Trust I I [Member]
Variable Interest Entity [Line Items]
Proceeds from issuance of trust preferred securities		$ 25,000,000.0
Senior unsecured notes due 2029 [Member]
Variable Interest Entity [Line Items]
Senior unsecured notes due 2029, carrying value				49,400,000
Senior unsecured notes due 2029, fair value				45,600,000
Subordinated Debt [Member]
Variable Interest Entity [Line Items]
Trust preferred securities, carrying value				56,000,000.0
Trust preferred securities, fair value				$ 35,900,000
Subordinated Debt [Member] | Hallmark Statutory Trust I [Member]
Variable Interest Entity [Line Items]
Payments to acquire trust preferred investments			$ 30,900,000
Subordinated Debt [Member] | Hallmark Statutory Trust I I [Member]
Variable Interest Entity [Line Items]
Payments to acquire trust preferred investments		$ 25,800,000
Subsequent Event [Member] | Agreement with A.M Best Rated Insurance Company [Member]
Variable Interest Entity [Line Items]
Minimum costs of assessments and state premium taxes					$ 250,000
Subsequent Event [Member] | Loss Portfolio Transfer Contract Right Dispute [Member] | Pending Litigation [Member]
Variable Interest Entity [Line Items]
Receivable for pending resolution						$ 58,900,000