Stockholders' Equity (Summary Of Nonvested Restricted Common Stock Transactions) (Details) (Restricted Stock-Based Compensation [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Restricted Stock-Based Compensation [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options, Nonvested at December 31, 2010	820
Number of options, Granted	265
Number of options, Cancelled	(38)
Number of options, Vested	(279)
Number of options, Nonvested at December 31, 2011	768
Weighted average grant date fair value, Nonvested at December 31, 2010	$ 19.66
Weighted average grant date fair value, Granted	$ 24.45
Weighted average grant date fair value, Cancelled	$ 17.77
Weighted average grant date fair value, Vested	$ 21.88
Weighted average grant date fair value, Nonvested at December 31, 2011	$ 20.47