Share-Based Compensation And Capital Stock Summary Of Activity Related To PVRSU Grants (Details) (Performance Vested Restricted Stock Units, USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Performance vested restricted stock units granted at target	117,523	25,036	33,517
Weighted average grant date fair value per share	$ 35.27	$ 41.25	$ 32.60
Average Aggregate grant date fair value ($000)	$ 4,145	$ 1,033	$ 1,093
Stock units forfeited	57,176	43,179	13,110
Requisite service period		3 years	3 years
Minimum [Member]
Requisite service period	24 months
Maximum [Member]
Requisite service period	60 months