Summary of Significant Accounting Policies - Intangibles, debt, revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Summary of Significant Accounting Policies
Non-cash adjustment	$ 4.2	$ 4.3
Capitalized contract cost, net	2.1	2.0
Amortization expense	$ 1.1	1.2	$ 1.1
Accounts receivable collection period	40 days
Contract with customer, asset, net	$ 4.3	7.0
Term loan
Summary of Significant Accounting Policies
Debt issuance costs, gross	0.3	0.4
Revolving and Term loan facility
Summary of Significant Accounting Policies
Debt issuance costs, gross	4.0
Accumulated amortization, debt issuance	2.9	2.4
Amortization of debt issuance costs	0.6	0.6	$ 1.1
Customer relationships
Summary of Significant Accounting Policies
Impairment of intangible assets	0.0	0.0
Depreciation and amortization expense
Summary of Significant Accounting Policies
Non-cash adjustment	3.4	2.7
Communications and utilities expense
Summary of Significant Accounting Policies
Non-cash adjustment		1.3
Operating expenses and supplies expense
Summary of Significant Accounting Policies
Non-cash adjustment	$ 0.8	$ 0.3
Minimum
Summary of Significant Accounting Policies
Salvage value (as a percent)	25.00%
Minimum | Customer relationships
Summary of Significant Accounting Policies
Intangible asset, useful life	7 years
Maximum
Summary of Significant Accounting Policies
Salvage value (as a percent)	50.00%
Maximum | Customer relationships
Summary of Significant Accounting Policies
Intangible asset, useful life	15 years