Common Stock (Options) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified					12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008	Dec. 31, 2011 $0.01 - $5.00 Years	Dec. 31, 2011 $5.01 - $10.00 Years	Dec. 31, 2011 $10.01 - 15.00 Years	Dec. 31, 2011 $15.01 - $20.00 Years	Dec. 31, 2011 $20.01 - $25.00 Years	Dec. 31, 2011 $25.01 - $30.00 Years	Dec. 31, 2011 $30.01 - $35.00 Years
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Low (in dollars per share)					$ 0.01	$ 5.01	$ 10.01	$ 15.01	$ 20.01	$ 25.01	$ 30.01
Range of Exercise Prices, Upper (in dollars per share)					$ 5.00	$ 10.00	$ 15.00	$ 20.00	$ 25.00	$ 30.00	$ 35.00
Amount Outstanding (in shares)	1,536	3,353	2,782	2,341	523	718	33	84	92	20	66
Weighted Average Remaining Contractual Life (in years)					7.2	8.2	7.5	2.8	2.1	5.0	9.0
Weighted Average Exercise Price (in dollars per share)	$ 9.30	$ 14.30	$ 15.40	$ 21.94	$ 3.40	$ 8.38	$ 11.44	$ 17.91	$ 21.93	$ 25.68	$ 31.64
Amoun Exercisable (in shares)	674	1,932	1,869		272	184	19	84	92	20	3
Weighted Average Exercise Price (in dollars per share)	$ 10.14	$ 19.98	$ 21.03		$ 3.39	$ 8.40	$ 11.45	$ 17.91	$ 21.93	$ 25.68	$ 34.86