Shareholders' Equity (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Stock option plans [Abstract]
Percentage option price (in hundredths)	100.00%
Reserved unissued shares of common stock for the exercise of unexercised and outstanding options (in shares)	17,862		17,862
Restricted stock units under the 2006 and 2011 Incentive Plan [Abstract]
Maximum shares granted to employees (in shares)	700,000		700,000
Compensation expense for 2006 and 2011 incentive plans	$ 151,000	$ 371,000	$ 528,000	$ 438,000
Restricted Stock Units vested (in shares)	0	0	68,629	62,307
Shares withheld upon vesting (in shares)			22,330	19,146
Fair value of vested Restricted Stock Units			2,405,000	2,233,000
2006 Incentive Plan [Member]
Restricted stock units under the 2006 and 2011 Incentive Plan [Abstract]
Award vesting period	5 years
2011 Incentive Plan [Member]
Restricted stock units under the 2006 and 2011 Incentive Plan [Abstract]
Award vesting period		5 years
Non Employee Directors Stock Incentive Plan [Member]
Non employee Directors Stock Incentive Plan [Abstract]
Term of stock options	10 years		10 years
Shares reserved under the 1998 Non-Employee Directors Stock Incentive Plan (in shares)	122,575		122,575
Shares are available for future grants of stock or deferred stock to directors (in shares)	100,958		100,958
Fair value of stock awards granted to non-employee directors	$ 58,000	$ 58,000	$ 116,000	$ 116,000