Earnings Per Share (Summary of Antidilutive 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
Earnings Per Share
Antidilutive stock options	1,756	[1]	1,373	[1]	1,587	[1]
Weighted-average exercise price	$ 62.79	[1]	$ 48.15	[1]	$ 35.61	[1]

[1] See Note 10 for further discussion on the terms of the Company's share-based compensation plans.