Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Statement [Abstract]
Revenue	$ 9,446.5	$ 9,493.7	$ 10,105.7
Costs and expenses:
Costs of services (exclusive of depreciation and amortization)	7,720.2	7,841.6	8,153.5
Operating, administrative and other	1,224.1	1,262.8	1,261.3
Depreciation and amortization	122.2	145.6	146.9
Restructuring, impairment and related charges	41.1	38.1	8.9
Total costs and expenses	9,107.6	9,288.1	9,570.6
Operating income	338.9	205.6	535.1
Interest expense, net of interest income	(229.9)	(281.1)	(193.1)
Earnings from equity method investments	37.4	58.1	85.0
Other income (expense), net	29.4	(12.6)	(89.0)
Earnings (loss) before income taxes	175.8	(30.0)	338.0
Provision for income taxes	44.5	5.4	141.6
Net income (loss)	$ 131.3	$ (35.4)	$ 196.4
Basic earnings (loss) per share:
Earnings (loss) per share attributable to common shareholders, basic (in dollars per share)	$ 0.57	$ (0.16)	$ 0.87
Weighted average shares outstanding for basic earnings (loss) per share (in shares)	228.9	226.9	225.4
Diluted earnings (loss) per share:
Earnings (loss) per share attributable to common shareholders, diluted (in dollars per share)	$ 0.56	$ (0.16)	$ 0.86
Weighted average shares outstanding for diluted earnings (loss) per share (in shares)	232.8	226.9	228.0