Stock-Based Compensation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Y	Dec. 31, 2010 Y	Dec. 31, 2009 Y	Dec. 31, 2008
A summary of stock option activity under the Plan
Options outstanding, beginning of period, weighted Average Exercise Price	$ 39.43	$ 39.61	$ 45.21
Stock option granted in period, number of options	0		64,474
Stock options granted, weighted average exercise price	$ 0.00		$ 8.64
Stock option exercised in period, number of options	0
Share based options exercisable, weighted average exercise price	$ 0.00
Stocks forfeited during period, number of options	(13,300)	(6,190)	(14,470)
Stocks forfeited during period, weighted average exercise price	$ 37.98	$ 40.85	$ 33.59
Stock options expired during period, number of options	(33,000)	(4,399)	(65,500)
Stock options expired during period, weighted average exercise price	$ 48.85	$ 57.76	$ 54.15
Options outstanding, end of period, weighted average strike price	$ 38.76	$ 39.43	$ 39.61
Option outstanding, end of period, weighted average term	3.6	3.8	4.7
Options outstanding, end of period, aggregate intrinsic value	$ 1,143	$ 880	$ 607
Options exercisable, end of period, number of options	378,710	396,115	363,709
Option exercisable, end of period, weighted average exercise price	$ 41.66	$ 43.21	$ 44.40
Options exercisable, end of period, weighted average term	3.1	3.4	4.1
Options exercisable, end of period, aggregate intrinsic value	457	176
Option unvested, end of period, number of options	59,684	88,579	131,574
Options unvested, end of period, weighted average exercise price	$ 20.36	$ 22.50	$ 26.37
Options unvested, end of period, weighted average term	6.1	6.9	7.3
Options unvested, end of period, aggregate intrinsic value	$ 686	$ 704	$ 607
Option outstanding, end of period, number of options	438,394	484,694	495,283	510,779