Condensed Consolidated Statements Of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement [Abstract]
Revenues	$ 3,085.1	$ 2,517.1	$ 5,996.5	$ 4,939.4
Operating expenses:
Cost of revenues (exclusive of depreciation and amortization expense shown separately below)	1,844.8	1,499.5	3,572.0	2,931.9
Selling, general and administrative expenses	612.0	482.9	1,222.8	968.3
Depreciation and amortization expense	82.8	46.7	155.9	91.2
Income from operations	545.5	488.0	1,045.8	948.0
Other income (expense), net:
Interest income	17.6	14.1	35.6	27.6
Interest expense	(4.1)	0.0	(9.1)	0.0
Foreign currency exchange gains (losses), net	(10.4)	(0.8)	(12.6)	(2.0)
Other, net	0.2	0.5	(0.3)	1.4
Total other income (expense), net	3.3	13.8	13.6	27.0
Income before provision for income taxes	548.8	501.8	1,059.4	975.0
Provision for income taxes	128.7	129.9	256.4	254.2
Net income	$ 420.1	$ 371.9	$ 803.0	$ 720.8
Basic earnings per share	$ 0.69	$ 0.61	$ 1.32	$ 1.19
Diluted earnings per share	$ 0.68	$ 0.61	$ 1.31	$ 1.18
Weighted average number of common shares outstanding - Basic	609.9	607.9	609.7	607.8
Dilutive effect of shares issuable under stock-based compensation plans	4.0	4.3	4.2	4.7
Weighted average number of common shares outstanding - Diluted	613.9	612.2	613.9	612.5