Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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Capital contributions to subsidiaries.

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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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The percentage points added to the reference rate to compute the variable rate on the interest rate derivative.

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Amount of right to receive securities collateral under master netting arrangements that have not been offset against derivative liabilities.

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Period the derivative contract is outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The net cash inflow or outflow for the increase (decrease) associated with funds that are not available for withdrawal or use (such as funds held in escrow) and are associated with underlying transactions that are classified as investing activities.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of loans from a bank with maturities initially due after one year or beyond the normal operating cycle if longer.

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Bonds or similar securities issued by state, city, or local governments or the agencies operated by state, city, or local governments which are short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

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The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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Dividends received on equity and other investments during the current period.

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Indebtedness divided by net capital.

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Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

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Condensed Financial Information of Registrant Condensed Financial Information of Registrant (Narratives) (Details)							1 Months Ended	12 Months Ended
	Mar. 29, 2017 USD ($)	Jan. 12, 2015 USD ($)	Jan. 02, 2015 USD ($)	Feb. 13, 2014	Aug. 09, 2013	Jul. 02, 2013 USD ($)	Jan. 31, 2017	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jan. 31, 2018	Jul. 07, 2017	Mar. 08, 2017 USD ($)	Dec. 03, 2014 USD ($)
Condensed Financial Statements, Captions [Line Items]
Proceeds from special purpose investment vehicles								$ 5,200,000	$ 4,900,000
Proceeds from dividends received								109,000,000	111,000,000	$ 133,000,000
Capital contributions to subsidiaries								140,125,000	30,125,000	$ 90,125,000
Escrow deposit recovery								2,000,000	$ 2,000,000
Revolving credit facility term						5 years
Interest rate at period end									1.73%
Revolving Credit Facility [Member]
Condensed Financial Statements, Captions [Line Items]
Loan maximum borrowing capacity						$ 200,000,000								$ 250,000,000
Revolving credit facility term	5 years
Workmen's Auto Insurance Company [Member]
Condensed Financial Statements, Captions [Line Items]
Consideration paid in cash			$ 8,000,000
Amount held in escrow			$ 2,000,000
Term for escrow security payment			3 years
Capital contribution amount		$ 15,000,000
Mcc [Member]
Condensed Financial Statements, Captions [Line Items]
Credit facility								120,000,000
Bank loan								20,000,000
Municipal bonds, fair value								175,000,000
Total borrowing guaranteed								140,000,000
Swap [Member] \| FFL [Member]
Condensed Financial Statements, Captions [Line Items]
Swap agreement collateral								30,000,000
Notional amount								$ 108,000,000
Term of swap agreement				1 year				1 year
Swap [Member] \| FFL [Member] \| LIBOR [Member]
Condensed Financial Statements, Captions [Line Items]
Basis spread on variable rate				1.45%				1.28%	1.45%
Swap [Member] \| AFL [Member]
Condensed Financial Statements, Captions [Line Items]
Swap agreement collateral								$ 40,000,000
Notional amount								$ 152,000,000
Term of swap agreement					3 years		1 year
Swap [Member] \| AFL [Member] \| LIBOR [Member]
Condensed Financial Statements, Captions [Line Items]
Basis spread on variable rate					1.35%				1.35%			1.28%
Unsecured Debt [Member]
Condensed Financial Statements, Captions [Line Items]
Interest rate, stated percentage													4.40%
Debt issuance costs													$ 3,400,000
Discount percent													99.847%
Interest rate, effective percentage													4.45%
Secured Notes Two [Member]
Condensed Financial Statements, Captions [Line Items]
Total borrowing guaranteed									$ 20,000,000
Secured Notes Two [Member] \| Revolving Credit Facility [Member]
Condensed Financial Statements, Captions [Line Items]
Loan maximum borrowing capacity	$ 50,000,000
Minimum [Member] \| Revolving Credit Facility [Member]
Condensed Financial Statements, Captions [Line Items]
Debt to total capital ratio	0.15
Commitment fee on undrawn portion of facility	0.125%
Minimum [Member] \| LIBOR [Member] \| Revolving Credit Facility [Member]
Condensed Financial Statements, Captions [Line Items]
Basis spread on variable rate	1.125%
Debt to total capital ratio	0.15
Minimum [Member] \| Secured Notes Two [Member] \| Revolving Credit Facility [Member]
Condensed Financial Statements, Captions [Line Items]
Commitment fee on undrawn portion of facility								0.15%
Maximum [Member] \| Revolving Credit Facility [Member]
Condensed Financial Statements, Captions [Line Items]
Debt to total capital ratio	0.25
Commitment fee on undrawn portion of facility	0.225%
Maximum [Member] \| LIBOR [Member] \| Revolving Credit Facility [Member]
Condensed Financial Statements, Captions [Line Items]
Basis spread on variable rate	1.625%
Debt to total capital ratio	0.25
Maximum [Member] \| Unsecured Notes Three [Member] \| Revolving Credit Facility [Member]
Condensed Financial Statements, Captions [Line Items]
Debt to total capital ratio								0.176
Subsequent Event [Member] \| Swap [Member] \| FFL [Member] \| LIBOR [Member]
Condensed Financial Statements, Captions [Line Items]
Basis spread on variable rate											1.20%