Share-Based Compensation and Capital Stock Summary Of Activity Related To PVRSU Grants (Details) (Performance Vested Restricted Stock Units [Member], USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Performance vested restricted stock units granted at target	0	6,137	58,902	100,046
Weighted average grant date fair value per share		$ 32.59	$ 36.76	$ 35.68
Aggregate grant date fair value		$ 200	$ 2,165	$ 3,570
Stock units forfeited	0	0	0	57,176
Requisite service period		41 months
Minimum [Member]
Requisite service period			22 months	36 months
Maximum [Member]
Requisite service period			36 months	60 months