Stock Compensation Plans (Details 1) (SOSARs and Stock Options [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 years	Dec. 31, 2010	Dec. 31, 2009
SOSARs and Stock Options [Member]
Summary of stock options outstanding and exercisable under long-term performance compensation plan
Options & SOSARs outstanding at January 1, 2011, Shares	851
Options exercised, Shares	(329)
Options & SOSARs cancelled / forfeited, Shares	(19)
Options and SOSARs outstanding at December 31, 2011, Shares	503	851
Vested and expected to vest at December 31, 2011, Shares	501
Options exercisable at December 31, 2011, Shares	363
Options & SOSARs outstanding at January 1, 2011, Weighted-Average Exercise Price	$ 33.38
Options exercised, Weighted-Average Exercise Price	$ 35.66
Options & SOSARs cancelled / forfeited, Weighted-Average Exercise Price	$ 41.65
Options and SOSARs outstanding at December 31, 2011, Weighted-Average Exercise Price	$ 31.56	$ 33.38
Vested and expected to vest at December 31, 2011, Weighted-Average Exercise Price	$ 31.58
Options exercisable at December 31, 2011, Weighted-Average Exercise Price	$ 34.57
Options and SOSARs outstanding at December 31, 2011, Weighted-Average Remaining Contractual Term	1.81
Vested and expected to vest at December 31, 2011, Weighted-Average Remaining Contractual Term	1.80
Options exercisable at December 31, 2011, Weighted-Average Remaining Contractual Term	1.41
Options and SOSARs outstanding at December 31, 2011, Aggregate Intrinsic Value	$ 6,380
Vested and expected to vest at December 31, 2011, Aggregate Intrinsic Value	6,352
Options exercisable at December 31, 2011, Aggregate Intrinsic Value	3,597
Total intrinsic value of options exercised during the year ended December 31	3,817	2,724	2,127
Total fair value of shares vested during the year ended December 31	$ 816	$ 3,084	$ 4,145
Weighted average fair value of options granted during the year ended December 31		$ 13.75	$ 3.80