Business Segments Total Assets by Segment (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Segment Reporting, Asset Reconciling Item [Line Items]
Assets		$ 2,941.4	$ 2,687.8
Apex
Segment Reporting, Asset Reconciling Item [Line Items]
Assets		1,504.5	1,368.5
Oxford
Segment Reporting, Asset Reconciling Item [Line Items]
Assets		433.8	421.2
ECS
Segment Reporting, Asset Reconciling Item [Line Items]
Assets		935.2	865.6
Corporate
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	[1]	$ 67.9	$ 32.5

[1] Corporate segment assets include workers’ compensation receivable and rabbi trust assets related to deferred compensation for employees of other segments. These programs are managed by the Company's corporate office and the related balances are recorded at corporate. These assets have offsetting liabilities for workers' compensation loss reserves and the Company's deferred compensation plan.