Acquisitions - Narrative (Details) - USD ($) $ in Millions					3 Months Ended	12 Months Ended
	Jul. 25, 2023	Nov. 10, 2022	Oct. 11, 2022	Apr. 18, 2022	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Cash and cash equivalents						$ 0.9
Business Combination, Cash Aquired						3.1	$ 30.5	$ 0.0
Services revenue						1,782.3	1,553.5	$ 1,177.2
Scenario Forecast
Business Acquisition [Line Items]
Milestone payment					$ 2.8
Other Intangible Assets
Business Acquisition [Line Items]
Acquired other intangible assets at purchasing price				$ 1.8
Roker Inc. (Roker)
Business Acquisition [Line Items]
Business acquisition, date of acquisition	Jul. 25, 2023
Business Combination, Cash Aquired	$ 3.1
Business acquisition, goodwill, expected tax deductible amount						1.0
Acquired other intangible assets at purchasing price						2.3
Roker Inc. (Roker) | Other Intangible Assets
Business Acquisition [Line Items]
Acquired other intangible assets at purchasing price						2.3
Services revenue						0.2
Loss before income taxes						0.4
Acquisition related costs						0.2
KMP Associates Limited
Business Acquisition [Line Items]
Business acquisition, date of acquisition			Oct. 11, 2022
Business acquisition, consideration transferred			$ 13.8
Business combination, assumption of debt			0.3
Business Combination, Cash Aquired			$ 0.9
Divrt, Inc.
Business Acquisition [Line Items]
Business acquisition, date of acquisition		Nov. 10, 2022
Business acquisition, consideration transferred		$ 17.6
Maximum amount of contingent consideration to former owner		7.0
Accrued in projected contingent consideration		$ 4.0
KMP Associates Limited and Divrt, Inc.
Business Acquisition [Line Items]
Cash and cash equivalents						0.9
Acquired other intangible assets at purchasing price						23.5	23.5
KMP Associates Limited and Divrt, Inc. | Other Intangible Assets
Business Acquisition [Line Items]
Services revenue						6.3
Loss before income taxes						$ 4.0
Acquisition related costs							$ 2.6