Investments (Major Categories of net Investment Income) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Schedule of Investments [Line Items]
Investment income	$ 13,704	$ 21,609
Investment expenses	(784)	(1,005)
Investment income, net of expenses	12,920	20,604
Cash and Cash Equivalents [Member]
Schedule of Investments [Line Items]
Investment income	0	766
Equity Securities [Member]
Schedule of Investments [Line Items]
Investment income	1,369	2,364
Debt Securities [Member] \| U.S. Treasury Securities and Obligations of U.S. Government [Member]
Schedule of Investments [Line Items]
Investment income	885	916
Debt Securities [Member] \| Corporate Bonds [Member]
Schedule of Investments [Line Items]
Investment income	7,223	7,317
Debt Securities [Member] \| Corporate bank loans [Member]
Schedule of Investments [Line Items]
Investment income	1,688	6,028
Debt Securities [Member] \| Municipal Bonds [Member]
Schedule of Investments [Line Items]
Investment income	2,347	3,907
Debt Securities [Member] \| Mortgage Backed [Member]
Schedule of Investments [Line Items]
Investment income	$ 192	$ 311

Represents the total of interest and dividend income, including any amortization and accretion (as applicable) of discounts and premiums, earned from (1) loans and leases whether held-for-sale or held-in-portfolio; (2) investment securities; (3) federal funds sold; (4) securities purchased under agreements to resell; (5) investments in banker's acceptances, commercial paper, or certificates of deposit; (6) dividend income; or (7) other investments not otherwise specified herein.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.1-5)
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

+ Details

Name:	us-gaap_InterestAndDividendIncomeOperating
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of expenses related to the generation of investment income.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.9)
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.2)
-URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

+ Details

Name:	us-gaap_InvestmentIncomeInvestmentExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, after investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(2))
-URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

+ Details

Name:	us-gaap_NetInvestmentIncome
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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.

+ References

No definition available.

+ Details

Name:	us-gaap_ScheduleOfInvestmentsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CashAndCashEquivalentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_DebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=hall_UsTreasurySecuritiesAndObligationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CorporateBondSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_BankLoanObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_MunicipalBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_MortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: