Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Allowance for Doubtful Accounts and Bilinig Adjustments
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year		$ 4.8	$ 9.9		$ 8.1
Provisions		3.7	3.3	[1]	5.3
SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Other Account	[2]	0.0	0.0		6.8
Deductions	[3]	(3.4)	(7.0)		(10.3)
Balance at end of year		5.1	4.8		9.9
Allowance for Workers' Compensation and Medical Malpractice Loss Reserves
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year		17.4	14.8		15.8
Provisions		3.3	3.6		2.9
SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Other Account	[2]	0.0	0.0		0.0
Deductions	[3]	(4.5)	(1.0)		(3.9)
Balance at end of year		$ 16.2	$ 17.4		$ 14.8

[1] Upon adoption of ASC 606, permanent placement fallouts of $1.5 million were reclassified from allowance from doubtful accounts to other current liabilities, effective January 1, 2018.

[2] Charges to other accounts include provision for permanent placement fallouts that have been deducted from net revenues and billing adjustments that have been deducted from net revenues in the accompanying consolidated statements of operations and comprehensive income.

[3] Deductions from allowance for doubtful accounts include write-offs of uncollectible accounts receivable for the years ended December 31, 2019 and 2018. For the year ended December 31, 2017 deductions from allowance for doubtful accounts include write-offs of uncollectible accounts receivable, permanent placements fallouts that have been charged against the allowance for doubtful accounts and billing adjustments. Deductions from workers’ compensation loss reserves include payments of claims and changes related to anticipated insurance and indemnification recoveries for all periods presented.