Segment Reporting (Schedule Of Net Revenues Earned On Major Geographical Areas) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Total net revenues	$ 546,746	[1]	$ 438,604	[1]
United States [Member]
Total net revenues	525,441		429,193
United Kingdom [Member]
Total net revenues	17,919		6,850
Other European [Member]
Total net revenues	$ 3,386		$ 2,561

[1] No individual client accounted for more than 10 percent of total net revenues for the three months ended March 31, 2014 or 2013.