Accounting Policies (Narrative) (Details) $ in Millions				12 Months Ended
	Jan. 01, 2018 USD ($)	Aug. 23, 2007 USD ($)	Jun. 21, 2005 USD ($)	Dec. 31, 2018 USD ($) segment	Dec. 31, 2017 USD ($)
Number of reportable segments | segment				3
Deferred policy acquisition costs, additions				$ 35.7	$ 31.1
Deferred policy acquisition costs, amortized				37.4	34.3
Deferred policy acquisition cost, (amortization) deferrals				(1.7)	(3.2)
Property and equipment, gross				$ 27.0	24.9
Property and equipment, depreciation method				straight-line method
Depreciation				$ 2.7	2.2
Property and equipment, accumulated depreciation				20.0	17.3
Policy fees				$ 6.5	$ 7.6
Corporate tax rate				21.00%	35.00%
Reclassification of certain tax effects from accumulated other comprehensive income at January 1,2018	$ 2.6
Charge from revaluation of deferred tax balances as a result of Tax Cuts and Jobs Act					$ 1.3
Hallmark Statutory Trust I [Member]
Long-term debt, gross			$ 30.9
Proceeds from issuance of trust preferred securities			$ 30.0
Hallmark Statutory Trust I I [Member]
Long-term debt, gross		$ 25.8
Proceeds from issuance of trust preferred securities		$ 25.0
Facility B Revolving Credit Facility [Member]
Credit facility, carried value				$ 30.0
Credit facility, fair value					$ 30.2
Minimum [Member]
Property and equipment, estimated useful lives				3 years	3 years
Maximum [Member]
Property and equipment, estimated useful lives				10 years	10 years
Accounting Standards Update 2016-01 [Member]
Net after-tax unrealized gains on equity investments				$ 17.0
Subordinated Debt [Member]
Long-term debt, gross				55.8	$ 55.8
Trust Preferred Securities, fair value				$ 45.6	$ 43.7