Stock Compensation Plans (Details 3) (Restricted Stock [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Restricted Stock [Member]
Restricted stock transactions
Unvested at beginning of year, Restricted Stock	2,223	1,343	1,701
Unvested at beginning of year, Weighted Average Grant date Fair Value	$ 64.27	$ 62.75	$ 66.49
Granted, Restricted Stock	1,136	1,261	304
Granted, Weighted Average Grant Date Fair Value	$ 84.61	$ 65.79	$ 48.14
Vested, Restricted Stock	(767)	(286)	(580)
Vested, Weighted Average Grant Date Fair Value	$ 67.36	$ 63.92	$ 65.15
Forfeited, Restricted Stock	(159)	(95)	(82)
Forfeited, Weighted Average Grant Date Fair Value	$ 72.51	$ 64.16	$ 69.23
Unvested at end of year, Restricted Stock	2,433	2,223	1,343
Unvested at end of year, Weighted Average Grant date Fair Value	$ 72.25	$ 64.27	$ 62.75