Acxiom Acquisition Preliminary fair values of the assets acquired and liabilities assumed (Details) - Acxiom - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Oct. 01, 2018
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents		$ 13.3
Accounts receivable, net of allowance		112.9
Accounts receivable, billable to clients		8.3
Other current assets		28.2
Property, Plant and Equipment, Other, Net		159.7
Deferred Income Taxes and Other Tax Liabilities, Noncurrent		(0.6)
Goodwill		1,110.8
Intangible Assets, Net (excluding Goodwill)		995.0
Other non-current assets		8.3
Accounts Payable		(37.1)
Accrued Liabilities		(46.9)
Contract liabilities		23.2
Other non-current liabilities		0.8
Net Asset Acquired		2,327.9
Identifiable Intangible Assets		995.0
Customer Lists with useful life of 15 years
Identifiable Intangible Assets, Useful Life	15 years
Identifiable Intangible Assets		600.0
Know-how technology with useful life with 9 years
Identifiable Intangible Assets, Useful Life	9 years
Identifiable Intangible Assets		235.0
Trade Names with useful life 15 years to indefinite
Identifiable Intangible Assets		$ 160.0