Segments (Schedule Of Company's Segment Results) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Segment Reporting Information [Line Items]
Revenues, net	$ 146,165	$ 111,005
Operating income	64,475	50,487
Depreciation and amortization	11,720	8,607
Capital expenditures	3,563	2,594
North America [Member]
Segment Reporting Information [Line Items]
Revenues, net	82,812	71,585
Operating income	38,113	31,192
Depreciation and amortization	4,994	4,942
Capital expenditures	2,095	1,485
International [Member]
Segment Reporting Information [Line Items]
Revenues, net	63,353	39,420
Operating income	26,362	19,295
Depreciation and amortization	6,726	3,665
Capital expenditures	$ 1,468	$ 1,109