Segment Reporting (Schedule Of Net Revenues Earned On Major Geographical Areas) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Segment Reporting Information [Line Items]
Total net revenues	$ 560,982	[1]	$ 546,756	[1]
United States [Member]
Segment Reporting Information [Line Items]
Total net revenues	522,616		517,484
United Kingdom [Member]
Segment Reporting Information [Line Items]
Total net revenues	35,286		25,884
Other European [Member]
Segment Reporting Information [Line Items]
Total net revenues	$ 3,080		$ 3,388

[1] No individual client accounted for more than 10 percent of total net revenues for the three months ended March 31, 2015 or 2014.