Summary Of Operations And Significant Accounting Policies (Summary Of Stock Option Activity And Weighted Average Exercise Prices) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013
Options
Options outstanding at December 31, 2012	9,841,479
Options granted	310,300
Options exercised	(124,943)
Options cancelled	(243,793)
Options outstanding at March 31, 2013	9,783,043
Options exercisable at March 31,2013	3,494,350
Weighted Average Exercise Price
Options outstanding at December 31, 2013	$ 11.06
Options granted	$ 13.37
Options exercised	$ 7.76
Options cancelled	$ 13.92
Options outstanding at March 31, 2013	$ 11.11
Options exercisable at March 31,2013	$ 6.62