Summary Of Significant Accounting Policies (Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accounting Policies [Abstract]
Net income	$ 203,483	$ 180,675	$ 153,132
Weighted average shares outstanding - basic	92,622	92,120	90,684
Dilutive effect of stock plans	2,332	2,261	2,525
Weighted average shares outstanding - diluted	94,954	94,381	93,209
Basic earnings per share (in USD per share)	$ 2.20	$ 1.96	$ 1.69
Diluted earnings per share (in USD per share)	$ 2.14	$ 1.91	$ 1.64
Anti-dilutive options	1,506	1,421	1,867