Investments (OTTI) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Current Provision for Securities without Prior Allowance	$ 1,025		$ 8,100
Credit Loss, (Expense) Benefit	2,854		(8,227)
Other Impairment Expense	(44)		(16,259)
OTTI benefit (expense) recognized in earnings	2,810	$ (2,291)	(24,486)	$ (3,366)
Other Investments [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Other Impairment Expense	0		0
OTTI benefit (expense) recognized in earnings	0	(610)	0	(846)
Other investments, Credit Loss (Expense) Benefit	0		0
Short-Term Investments [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Other Impairment Expense	0		0
OTTI benefit (expense) recognized in earnings	(1)	0	(1)	0
Short term investments, allowance for credit loss	(1)		(1)
Commercial Mortgage Loans [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Other Impairment Expense	0		0
OTTI benefit (expense) recognized in earnings	(2)	0	(220)	0
CML, Credit Loss (Expense) Benefit	(2)		(220)
Available-for-sale Securities [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Current Provision for Securities without Prior Allowance	2,854		(8,010)
Other Impairment Expense	(44)		(16,259)
OTTI benefit (expense) recognized in earnings	2,810	(1,681)	(24,269)	(2,520)
Available-for-sale Securities [Member] | U.S. Government and Government Agencies [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Current Provision for Securities without Prior Allowance			0
Other Impairment Expense			(14)
OTTI benefit (expense) recognized in earnings			(14)	0
Available-for-sale Securities [Member] | Foreign Government [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Current Provision for Securities without Prior Allowance	3		(25)
Other Impairment Expense	0		0
OTTI benefit (expense) recognized in earnings	3	0	(25)	0
Available-for-sale Securities [Member] | Obligations of States and Political Subdivisions [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Current Provision for Securities without Prior Allowance	2		(15)
Other Impairment Expense	0		(62)
OTTI benefit (expense) recognized in earnings	2	0	(77)	(65)
Available-for-sale Securities [Member] | Corporate Securities [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Current Provision for Securities without Prior Allowance	2,454		(6,018)
Other Impairment Expense	0		(12,103)
OTTI benefit (expense) recognized in earnings	2,454	(1,681)	(18,121)	(2,455)
Available-for-sale Securities [Member] | Collateralized Loan Obligations and Other Asset Backed Securities [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Current Provision for Securities without Prior Allowance	217		(1,230)
Other Impairment Expense	(44)		(2,137)
OTTI benefit (expense) recognized in earnings	173	0	(3,367)	0
Available-for-sale Securities [Member] | Residential Mortgage Backed Securities [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Current Provision for Securities without Prior Allowance	157		(690)
Other Impairment Expense	0		(91)
OTTI benefit (expense) recognized in earnings	157	0	(781)	0
Available-for-sale Securities [Member] | Commercial Mortgage Backed Securities [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Current Provision for Securities without Prior Allowance	21		(32)
Other Impairment Expense	0		(1,852)
OTTI benefit (expense) recognized in earnings	21	0	(1,884)	0
Held-to-maturity Securities [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Held to Maturity, Credit Loss (Expense) Benefit	3		4
Other Impairment Expense	0		0
OTTI benefit (expense) recognized in earnings	3	0	4	0
Held-to-maturity Securities [Member] | Corporate Securities [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Held to Maturity, Credit Loss (Expense) Benefit	3		4
Other Impairment Expense	0		0
OTTI benefit (expense) recognized in earnings	$ 3	$ 0	4	$ 0
Other than temporary impairment losses, investments [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
OTTI benefit (expense) recognized in earnings			$ (24,500)