Shareholder's Equity (Schedule of Stock Option Activity (Parenthetical) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Shareholders' Equity
Total intrinsic value with options exercised	$ 6,287,000	$ 2,482,000	$ 511,000
Aggregate intrinsic value of options outstanding	10,289,000
Total intrinsic value of options vested or expected to vest	10,289,000
Total Intrinsic value of options exercisable	$ 10,289,000