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

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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

- Definition

Amount of liability hedged in fair value hedging relationship.

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+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Balance Type:	credit
Period Type:	instant

- Definition

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.

+ References

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

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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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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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Balance Type:	debit
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- Definition

Debt Instrument, Basis Spread On Variable Rate, Floor

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Percentage Of Discounted Future Cash Flows

+ References

No definition available.

+ Details

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- Details

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Balance Type:
Period Type:

- Details

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Balance Type:
Period Type:

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Balance Type:
Period Type:

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Balance Type:
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Debt - NSM Bank Narrative (Details) £ in Millions						12 Months Ended
Debt - NSM Bank Narrative (Details) £ in Millions	Jun. 02, 2021 USD ($)	Jun. 01, 2021	Apr. 07, 2020 USD ($)	Apr. 07, 2020 GBP (£)	Apr. 06, 2020 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2021 GBP (£)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jun. 15, 2018 USD ($)
Debt Instrument
Total commitment under revolving credit facility			$ 291,400,000
Debt						$ 693,000,000.0		$ 376,400,000
NSM
Debt Instrument
Debt						272,100,000		272,600,000
NSM Bank Facility \| NSM
Debt Instrument
Total commitment under revolving credit facility					$ 234,000,000
Long-term line of credit						$ 274,100,000
Percentage of discounted future cash flows						10.00%	10.00%
Debt						$ 277,600,000		277,400,000	$ 221,300,000	$ 180,400,000
NSM Bank Facility \| NSM \| Term Loan
Debt Instrument
Total commitment under revolving credit facility					$ 224,000,000
Long-term line of credit	$ 50,000,000		276,400,000			277,600,000		277,400,000
Proceeds from borrowings			$ 52,400,000	£ 42.5		0	£ 41.9	52,400,000	42,900,000
Floor rate			1.25%	1.25%
Debt						271,200,000		271,300,000
NSM Bank Facility \| NSM \| Term Loan \| Interest Rate Swap
Debt Instrument
Total commitment under revolving credit facility											$ 151,000,000
Hedged liability, fair value hedge											$ 151,000,000
Debt						146,100,000
NSM Bank Facility \| NSM \| Term Loan \| Interest Rate Swap \| Designated as Hedging Instrument
Debt Instrument
Debt						146,100,000
NSM Bank Facility \| NSM \| Term Loan \| Interest Rate Swap \| Not Designated as Hedging Instrument
Debt Instrument
Debt						128,000,000
NSM Bank Facility \| NSM \| Term Loan \| United States Dollar London Interbank Offered Rate LIBOR
Debt Instrument
Floor rate			1.25%	1.25%
NSM Bank Facility \| NSM \| Term Loan \| United States Dollar London Interbank Offered Rate LIBOR \| Minimum
Debt Instrument
Basis spread on variable rate	4.50%	5.50%	5.50%	5.50%	4.25%
NSM Bank Facility \| NSM \| Term Loan \| United States Dollar London Interbank Offered Rate LIBOR \| Maximum
Debt Instrument
Basis spread on variable rate	5.00%	6.00%	6.00%	6.00%	4.75%
NSM Bank Facility \| NSM \| Term Loan \| British Sterling Pound London Interbank Offered Rate LIBOR \| Minimum
Debt Instrument
Basis spread on variable rate	5.00%	6.00%
NSM Bank Facility \| NSM \| Term Loan \| British Sterling Pound London Interbank Offered Rate LIBOR \| Maximum
Debt Instrument
Basis spread on variable rate	5.50%	6.50%
NSM Bank Facility \| NSM \| Term Loan \| Foreign Exchange Spot Rate
Debt Instrument
Proceeds from borrowings						56,700,000
NSM Bank Facility \| NSM \| Revolving Credit Facility
Debt Instrument
Total commitment under revolving credit facility	$ 40,000,000		$ 15,000,000		$ 10,000,000
Proceeds from borrowings						35,000,000.0		0	$ 6,500,000
Amount outstanding						3,500,000
Other NSM \| NSM \| Term Loan
Debt Instrument
Long-term line of credit						1,000,000
Debt						$ 900,000		$ 1,300,000