Segment Reporting (Schedule Of Net Revenues Earned On Major Geographical Areas) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Total net revenues	$ 478,639	[1]	$ 414,157	[1]	$ 1,410,921	[1]	$ 1,182,830	[1]
United States [Member]
Total net revenues	472,268		408,120		1,382,377		1,165,223
United Kingdom [Member]
Total net revenues	3,496		3,892		20,681		10,723
Other European [Member]
Total net revenues	$ 2,875		$ 2,145		$ 7,863		$ 6,884

[1] No individual client accounted for more than 10 percent of total net revenues for the three and nine months ended September 30, 2013 or 2012.