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

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Face (par) amount of debt instrument at time of issuance.

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Amount of increase (decrease) in debt instruments, classified as other.

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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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Incremental percentage increase (decrease) in the stated rate on a debt instrument.

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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.

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Weighted average interest rate of debt outstanding.

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Cap rate on an interest rate derivative such as an interest rate cap or collar. If market rates exceed the cap rate, a payment or receipt is triggered on the contract.

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No definition available.

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Fixed interest rate related to the interest rate derivative.

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Variable interest rate in effect as of the balance sheet date related to the interest rate derivative.

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Amount of liability hedged in fair value hedging relationship.

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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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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

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The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

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Number of Secured Credit Facilities

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Percentage of discounted future cash flows

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Debt - Narrative (Details)			3 Months Ended		9 Months Ended
Debt - Narrative (Details)	Apr. 07, 2020 GBP (£)	Apr. 07, 2020 USD ($)	Sep. 30, 2020 USD ($) credit_facility	Sep. 30, 2019 USD ($)	Sep. 30, 2020 GBP (£)	Sep. 30, 2020 USD ($) credit_facility	Sep. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Jun. 04, 2020 GBP (£)	Jun. 04, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 23, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jun. 15, 2018 USD ($)	May 11, 2018 USD ($)
Debt Instrument
Total commitment under revolving credit facility		$ 291,400,000									$ 234,000,000.0
Number of Secured Credit Facilities \| credit_facility			2			2
Debt			$ 359,400,000			$ 359,400,000						$ 283,500,000
Specialty Insurance Distribution (NSM)
Debt Instrument
Debt			$ 270,200,000			$ 270,200,000						$ 219,200,000
Specialty Insurance Distribution (NSM) \| Interest Rate Swap
Debt Instrument
Derivative, fixed interest rate																2.97%
Derivative, variable interest rate			1.00%			1.00%
NSM Bank Facility
Debt Instrument
Amount borrowed																	$ 100,000,000.0
NSM Bank Facility \| Specialty Insurance Distribution (NSM)
Debt Instrument
Amount borrowed			$ 275,000,000.0			$ 275,000,000.0
Percentage of discounted future cash flows					10.00%	10.00%
Debt, weighted average interest rate, all-in			6.91%			6.91%						6.60%
Debt			$ 275,000,000.0	$ 221,900,000		$ 275,000,000.0	$ 221,900,000	$ 273,400,000				$ 221,300,000		$ 222,300,000	$ 180,400,000
NSM Bank Facility \| Term Loan
Debt Instrument
Debt			$ 268,800,000			$ 268,800,000						$ 217,400,000
Effective percentage			7.40%			7.40%						7.50%
Long-term Debt, Gross			$ 275,000,000.0			$ 275,000,000.0						$ 221,300,000
NSM Bank Facility \| Term Loan \| Specialty Insurance Distribution (NSM)
Debt Instrument
Amount borrowed		276,400,000							£ 42,500,000	$ 52,400,000	224,000,000.0
Proceeds from borrowings	£ 42,500,000	$ 52,400,000	0	0	£ 42,500,000	52,400,000	42,900,000
Foreign currency translation			$ 2,300,000	0		$ 2,600,000	0
NSM Bank Facility \| Term Loan \| Specialty Insurance Distribution (NSM) \| Designated as Hedging Instrument
Debt Instrument
Debt, weighted average interest rate, all-in			6.84%			6.84%
NSM Bank Facility \| Term Loan \| Specialty Insurance Distribution (NSM) \| Interest Rate Swap
Debt Instrument
Total commitment under revolving credit facility																$ 151,000,000.0
Debt, weighted average interest rate, all-in								6.98%
Hedged liability, fair value																$ 151,000,000.0
Derivative, fixed interest rate																2.97%
Debt			$ 148,000,000.0			$ 148,000,000.0
NSM Bank Facility \| Term Loan \| Specialty Insurance Distribution (NSM) \| Interest Rate Swap \| Designated as Hedging Instrument
Debt Instrument
Debt, weighted average interest rate, all-in			8.72%			8.72%
Debt			$ 148,000,000.0			$ 148,000,000.0
NSM Bank Facility \| Term Loan \| Specialty Insurance Distribution (NSM) \| Interest Rate Swap \| Not Designated as Hedging Instrument
Debt Instrument
Debt			$ 127,000,000.0			$ 127,000,000.0
Effective percentage			7.03%			7.03%
NSM Bank Facility \| Term Loan \| Specialty Insurance Distribution (NSM) \| USD-LIBOR \| Minimum
Debt Instrument
Basis spread on variable rate	4.25%	4.25%	5.50%
NSM Bank Facility \| Term Loan \| Specialty Insurance Distribution (NSM) \| USD-LIBOR \| Maximum
Debt Instrument
Debt instrument, interest rate, increase (decrease)					1.25%	1.25%
Basis spread on variable rate	4.75%	4.75%	6.00%
NSM Bank Facility \| Term Loan \| Specialty Insurance Distribution (NSM) \| GBP-LIBOR \| Minimum
Debt Instrument
Basis spread on variable rate					6.00%	6.00%
NSM Bank Facility \| Term Loan \| Specialty Insurance Distribution (NSM) \| GBP-LIBOR \| Maximum
Debt Instrument
Debt instrument, interest rate, increase (decrease)					1.25%	1.25%
Basis spread on variable rate					6.50%	6.50%
Derivative, cap interest rate			1.25%			1.25%
NSM Bank Facility \| Revolving credit loan \| Specialty Insurance Distribution (NSM)
Debt Instrument
Total commitment under revolving credit facility		$ 15,000,000.0									$ 10,000,000.0
Proceeds from borrowings			$ 0	$ 0		$ 0	$ 6,500,000
Other NSM
Debt Instrument
Debt												$ 1,800,000
Other NSM \| Term Loan
Debt Instrument
Effective percentage			2.80%			2.80%						3.00%
Other NSM \| Term Loan \| Specialty Insurance Distribution (NSM)
Debt Instrument
Debt			$ 1,600,000			$ 1,600,000
Kudu Bank Facility \| Kudu
Debt Instrument
Total commitment under revolving credit facility													$ 124,000,000.0
Kudu Bank Facility \| Term Loan
Debt Instrument
Debt												$ 53,600,000
Effective percentage			8.40%			8.40%						8.30%
Long-term Debt, Gross			$ 74,000,000.0			$ 74,000,000.0						$ 57,000,000.0
Kudu Bank Facility \| Term Loan \| Kudu
Debt Instrument
Total commitment under revolving credit facility													57,000,000.0
Debt			74,000,000.0			74,000,000.0
Proceeds from issuance of long-term debt						$ 17,000,000.0
Kudu Bank Facility \| Line of Credit \| Kudu \| USD-LIBOR
Debt Instrument
Basis spread on variable rate					1.00%	1.00%
Kudu Bank Facility \| Line of Credit \| Kudu \| USD-LIBOR \| Minimum
Debt Instrument
Basis spread on variable rate					5.50%	5.50%
Kudu Bank Facility \| Line of Credit \| Kudu \| USD-LIBOR \| Maximum
Debt Instrument
Basis spread on variable rate					6.25%	6.25%
Kudu Bank Facility \| Line of Credit \| Kudu \| Prime Rate
Debt Instrument
Basis spread on variable rate					1.00%	1.00%
Kudu Bank Facility \| Line of Credit \| Kudu \| Prime Rate \| Minimum
Debt Instrument
Basis spread on variable rate					4.50%	4.50%
Kudu Bank Facility \| Line of Credit \| Kudu \| Prime Rate \| Maximum
Debt Instrument
Basis spread on variable rate					5.25%	5.25%
Kudu Bank Facility \| Delayed Draw Term Loans \| Kudu
Debt Instrument
Total commitment under revolving credit facility													62,000,000.0
Kudu Bank Facility \| Revolving credit loan \| Kudu
Debt Instrument
Total commitment under revolving credit facility													$ 5,000,000.0
First Credit Facility
Debt Instrument
Total commitment under revolving credit facility			16,300,000			$ 16,300,000
First Credit Facility \| Term Loan
Debt Instrument
Total commitment under revolving credit facility			11,300,000			11,300,000
Long-term Debt, Gross			9,800,000			9,800,000
First Credit Facility \| Delayed Draw Term Loans
Debt Instrument
Total commitment under revolving credit facility			3,000,000.0			3,000,000.0
First Credit Facility \| Revolving credit loan
Debt Instrument
Total commitment under revolving credit facility			2,000,000.0			2,000,000.0
Second Credit Facility
Debt Instrument
Total commitment under revolving credit facility			15,000,000.0			15,000,000.0
Second Credit Facility \| Term Loan
Debt Instrument
Total commitment under revolving credit facility			9,000,000.0			9,000,000.0
Long-term Debt, Gross			9,000,000.0			9,000,000.0
Second Credit Facility \| Delayed Draw Term Loans
Debt Instrument
Total commitment under revolving credit facility			4,000,000.0			4,000,000.0
Second Credit Facility \| Revolving credit loan
Debt Instrument
Total commitment under revolving credit facility			$ 2,000,000.0			$ 2,000,000.0