Stock Plans (Summary Of Performance Stock Unit Activity) (Details) (USD $)	6 Months Ended
	Jun. 30, 2011
Unvested at January 1, 2011, Shares	473,637
Unvested at January 1, 2011, Weighted Average Grant Date Fair value	$ 26.56
Granted, Shares	124,491
Granted, Weighted Average Grant Date Fair Value	$ 33.61
Unvested at June 30, 2011, Shares	514,365
Unvested at June 30, 2011, Weighted Average Grant Date Fair Value	$ 25.50
Performance Stock Unit [Member]
Unvested at January 1, 2011, Shares	85,629
Unvested at January 1, 2011, Weighted Average Grant Date Fair value	$ 20.53
Granted, Shares	41,320
Granted, Weighted Average Grant Date Fair Value	$ 33.55
Unvested at June 30, 2011, Shares	126,949
Unvested at June 30, 2011, Weighted Average Grant Date Fair Value	$ 24.77