Significant Business Transactions - Acquisition of IFDS U.K. (Details) - USD ($) $ in Millions			9 Months Ended
		Mar. 27, 2017	Sep. 30, 2017	Sep. 30, 2016	Mar. 30, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Ownership percentage			50.00%			50.00%
Acquisition of businesses, net of cash and cash equivalents acquired			$ 38.9	$ 93.5
Goodwill			$ 796.5			$ 516.4
International Financial Data Services U.K.
Business Acquisition [Line Items]
Cash paid to acquire the remaining equity interests in IFDS U.K. and other related interests (1)		$ 141.0
Payments to acquire notes receivable		25.9
Negotiated fair value		136.8
Remeasurement loss		12.2
Goodwill		195.9
Goodwill expected tax deductible amount		18.9
IFDS Realty U.K. and IFDS Percana
Business Acquisition [Line Items]
Total consideration transferred		68.0
IFDS U.K. IFDS, Percana and IFDS Realty U.K.
Business Acquisition [Line Items]
Cash paid to acquire the remaining equity interests in IFDS U.K. and other related interests (1)	[1]	234.9
Total consideration transferred		426.2
Acquisition of businesses, net of cash and cash equivalents acquired		$ 175.0
International Financial Data Services L.P.
Business Acquisition [Line Items]
Ownership percentage		50.00%	50.00%		50.00%

[1] Cash paid is comprised of cash payments to acquire State Street’s equity interest in IFDS U.K. and a note receivable from IFDS U.K., as well as IFDS L.P.’s equity interests in IFDS Percana and IFDS Realty U.K.