Shareholder's Equity (Schedule of Stock Option Activity (Parenthetical) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Shareholders' Equity
Total intrinsic value with options exercised	$ 2,482,000	$ 511,000	$ 112,000
Aggregate intrinsic value of options outstanding	7,562,000
Total intrinsic value of options vested or expected to vest	7,562,000
Total Intrinsic value of options exercisable	$ 7,514,000