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Derivatives - Narrative (Details) |  | 12 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Aug. 18, 2020 | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) | Jun. 04, 2020 USD ($) | Jun. 04, 2020 GBP (£) | Apr. 07, 2020 USD ($) | Apr. 06, 2020 USD ($) | Dec. 31, 2018 USD ($) | Jun. 15, 2018 USD ($)
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |
Total commitment under revolving credit facility |  |  |  |  |  |  | $ 291,400,000 |  |  |
Debt |  | $ 693,000,000.0 | $ 376,400,000 |  |  |  |  |  |  |
NSM |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |
Debt |  | $ 272,100,000 | $ 272,600,000 |  |  |  |  |  |  |
Debt, weighted average interest rate |  | 8.20% | 8.00% |  |  |  |  |  |  |
NSM Bank Facility | NSM |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |
Total commitment under revolving credit facility |  |  |  |  |  |  |  | $ 234,000,000 |  |
Debt |  | $ 277,600,000 | $ 277,400,000 | $ 221,300,000 |  |  |  |  | $ 180,400,000 |
NSM Bank Facility | NSM | Term Loan |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |
Total commitment under revolving credit facility |  |  |  |  |  |  |  | $ 224,000,000 |  |
Debt |  | $ 271,200,000 | 271,300,000 |  |  |  |  |  |  |
Interest Rate Swap | NSM |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |
Fixed interest rate |  |  |  |  |  |  |  |  |  | 2.97%
Variable interest rate |  | 1.00% |  |  |  |  |  |  |  |
Net interest expense |  | $ 2,500,000 | 2,500,000 | $ 1,100,000 |  |  |  |  |  |
Derivative, fair value, net |  | 4,800,000 | 8,200,000 |  |  |  |  |  |  |
Change in fair value of derivative instruments |  | (3,400,000) | (1,600,000) |  |  |  |  |  |  |
Interest Rate Swap | NSM Bank Facility | NSM | Term Loan |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |
Total commitment under revolving credit facility |  |  |  |  |  |  |  |  |  | $ 151,000,000
Debt |  | 146,100,000 |  |  |  |  |  |  |  |
Interest Rate Cap | NSM |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative, fair value, net |  | 200,000 | 100,000 |  |  |  |  |  |  |
Premiums paid |  | $ 100,000 |  |  |  |  |  |  |  |
GBP-LIBOR rate |  | 0.26% |  |  |  |  |  |  |  |
Decrease in fair value of derivative |  | $ (200,000) | $ (100,000) |  |  |  |  |  |  |
Interest Rate Cap | NSM | London Interbank Offered Rate (LIBOR) |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative, cap interest rate |  | 1.25% |  |  |  |  |  |  |  |
Interest Rate Cap | NSM Bank Facility | NSM |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument extension term (in years) | 1 year |  |  |  |  |  |  |  |  |
Interest Rate Cap | NSM Bank Facility | NSM | United Kingdom, Pounds |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |
Notational amount | £ |  |  |  |  |  | £ 42,500,000 |  |  |  |
Interest Rate Cap | NSM Bank Facility | NSM | United States of America, Dollars |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |
Notational amount |  |  |  |  | $ 52,400,000 |  |  |  |  |
Designated as Hedging Instrument | NSM |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |
Debt, weighted average interest rate |  | 9.00% | 9.00% |  |  |  |  |  |  |
Designated as Hedging Instrument | Interest Rate Swap | NSM Bank Facility | NSM | Term Loan |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |
Debt |  | $ 146,100,000 |  |  |  |  |  |  |  |
Debt, weighted average interest rate |  | 9.00% |  |  |  |  |  |  |  |

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