Stockholders Equity and Stock Options (Stock Option Activity And Options Outstanding) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares under option, period start	2,473,257	2,718,183	1,961,149
Options granted	986,000	944,500	1,359,500
Options exercised	(271,165)	(391,176)	(394,949)
Options cancelled and expired	(301,982)	(798,250)	(207,517)
Shares under option, period end	2,886,110	2,473,257	2,718,183
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Shares under option, weighted average exercise price start of period	$ 42.22	$ 41.85	$ 35.75
Options granted, weighted average exercise price	$ 38.56	$ 46.50	$ 47.65
Options exercised, weighted average exercise price	$ 27.94	$ 35.30	$ 31.81
Options cancelled and expired, weighted average exercise price	$ 45.07	$ 49.42	$ 42.34
Shares under option, weighted average exercise price end of period	$ 41.14	$ 42.22	$ 41.85
Options exercised, aggregate intrinsic value	$ 3,087	$ 4,224	$ 6,529
Shares under option, aggregate intrinsic value	$ 1,096	$ 7,731	$ 17,643