Segment Information (Revenues And Long-Lived Assets By Geographic Area) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013	Dec. 31, 2013
Geographic Areas, Revenues
Revenues	$ 2,581,009		$ 2,305,723	$ 7,520,451		$ 6,487,701
Geographic Areas, Long-Lived Assets
Long-lived Assets	1,101,468	[1]		1,101,468	[1]		1,081,164	[1]
North America [Member]
Geographic Areas, Revenues
Revenues	1,981,229		1,783,081	5,746,012		5,042,666
Geographic Areas, Long-Lived Assets
Long-lived Assets	50,781	[1],[2]		50,781	[1],[2]		48,352	[1],[2]
Europe [Member]
Geographic Areas, Revenues
Revenues	472,114		414,656	1,408,508		1,150,140
Geographic Areas, Long-Lived Assets
Long-lived Assets	24,586	[1]		24,586	[1]		22,707	[1]
United Kingdom [Member]
Geographic Areas, Revenues
Revenues	276,996		246,397	820,531		696,650
Rest of World [Member]
Geographic Areas, Revenues
Revenues	127,666		107,986	365,931		294,895
Geographic Areas, Long-Lived Assets
Long-lived Assets	$ 1,026,101	[1],[3],[4]		$ 1,026,101	[1],[3],[4]		$ 1,010,105	[1],[3],[4]

[1] Long-lived assets include property and equipment, net of accumulated depreciation and amortization.

[2] Substantially all relates to operations in the United States.

[3] Substantially all of these long-lived assets relate to our operations in India.

[4] Includes our operations in Asia Pacific, the Middle East and Latin America.