Statement Of Consolidated Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Statement Of Consolidated Comprehensive Income [Abstract]
Net income	$ 14,421	$ 26,441	$ 33,021	$ 45,083
Other comprehensive income, before tax and net of reclassification adjustments:
Foreign currency translation adjustment	(325)	(5,597)	(3,249)	(1,281)
Unrealized gain (loss) on securities available-for-sale	36	(404)	(406)	889
Unrealized gain on derivative instruments	1,574	747	3,652	4,631
Other comprehensive income (loss), before tax	1,285	(5,254)	(3)	4,239
Tax expense related to items of other comprehensive income	191	(1,005)	1,353	1,020
Other comprehensive income (loss), net of tax	1,094	(4,249)	(1,356)	3,219
Comprehensive income	$ 15,515	$ 22,192	$ 31,665	$ 48,302