Statement Of Consolidated Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Statement Of Consolidated Comprehensive Income [Abstract]
Net income	$ 90,137	$ 94,072	$ 109,116
Other comprehensive income, before tax and net of reclassification adjustments:
Foreign currency translation adjustment	2,231	(1,236)	(6,174)
Unrealized (loss) gain on securities available-for-sale	56	(1,017)	768
Unrealized gain (loss) on derivative instruments	3,247	(1,045)	(11,365)
Other comprehensive income (loss), before tax	5,534	(3,298)	(16,771)
Tax provision related to items of other comprehensive income	(1,190)	508	2,516
Other comprehensive income (loss), net of tax	4,344	(2,790)	(14,255)
Total comprehensive income	$ 94,481	$ 91,282	$ 94,861