Acquisition Fair Value of Consideration Transferred Footnotes (Details) - USD ($) shares in Millions, $ in Millions		3 Months Ended		9 Months Ended
	Aug. 01, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Business Acquisition [Line Items]
Gain on remeasurement of equity investment		$ 98.1	$ 0.0	$ 98.1	$ 0.0
Kelway TopCo Limited [Member]
Business Acquisition [Line Items]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares	1.6
Restriction period for common shares issued	3 years
Options issued by one of the sellers to certain coworkers over shares of the seller's common stock received as part of consideration from acquisition	0.6
Fair value of options issued by one of the sellers to certain coworkers over shares of the seller's common stock received as part of consideration from acquisition	$ 21.8
Weighted-average service period of options issued by one of the sellers to certain coworkers over shares of the seller's common stock received as part of consideration from acquisition	3 years 2 months 12 days
Business Combination, Step Acquisition, Equity Interest in Acquiree, Percentage	35.00%
Gain on remeasurement of equity investment	$ 98.1