Stock-Based Compensation Plans (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Stock-based compensation expense
Total stock-based compensation	$ 6,859	$ 8,969	$ 8,414
Employee [Member]
Stock-based compensation expense
Total stock-based compensation	6,180	8,316	7,898
Non employee director [Member]
Stock-based compensation expense
Total stock-based compensation	679	653	516
Restricted stock and performance shares [Member] | Employee [Member]
Stock-based compensation expense
Total stock-based compensation	5,856	6,588	5,040
Stock options [Member] | Employee [Member]
Stock-based compensation expense
Total stock-based compensation	324	1,728	2,858
Stock options [Member] | Non employee director [Member]
Stock-based compensation expense
Total stock-based compensation		83	143
Restricted stock [Member] | Non employee director [Member]
Stock-based compensation expense
Total stock-based compensation	$ 679	$ 570	$ 373