Stock-Based Compensation (Schedule of Deferred Stock Units Activity) (Details) (Deferred Stock Units [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Deferred Stock Units [Member]
Outstanding beginning balance	257	287	207
Outstanding beginning weighted average grant date fair value	$ 25.31	$ 21.04	$ 24.86
Granted	58	47	97
Granted weighted average grant date fair value	$ 32.48	$ 39.95	$ 21.56
Exercised	(15)	(77)	(17)
Vested and distributed weighted average grant date fair value	$ 33.78	$ 18.40	$ 33.07
Forfeited	(1)
Forfeited weighted average grant date fair value	$ 39.95
Outstanding ending balance	299	257	287
Outstanding ending weighted average grant date fair value	$ 26.25	$ 25.31	$ 21.04