Stock-Based Compensation (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Summary of stock-based compensation expense
Stock-based compensation expense	$ 890	$ 809	$ 2,583	$ 2,390
Stock appreciation rights [Member]
Summary of stock-based compensation expense
Stock-based compensation expense	369	408	1,089	1,146
Restricted stock [Member]
Summary of stock-based compensation expense
Stock-based compensation expense	508	391	1,442	1,198
Employee Stock Purchase Plan [Member]
Summary of stock-based compensation expense
Stock-based compensation expense	$ 13	$ 10	$ 52	$ 46