Acquisition - Fair Value of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Millions	May 08, 2018	Sep. 30, 2019	Dec. 31, 2018
Allocation of consideration to assets acquired and liabilities assumed:
Goodwill		$ 253.2	$ 254.8
Intermedix
Business Acquisition [Line Items]
Total purchase consideration	$ 469.2
Allocation of consideration to assets acquired and liabilities assumed:
Cash, cash equivalents, and restricted cash	6.4
Accounts receivable, net	35.5
Prepaid expenses and other current assets	11.6
Property, equipment and software, net	25.4
Intangible assets, net	191.1
Goodwill	253.2
Other assets	0.3
Accounts payable	(6.4)
Current portion of customer liabilities	(8.6)
Accrued compensation and benefits	(7.7)
Other accrued expenses	(6.2)
Deferred income tax liabilities	(25.4)
Net assets acquired	$ 469.2