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
	Mar. 31, 2014	Mar. 31, 2013
Share-Based Compensation and Capital Stock [Line Items]
Performance vested restricted stock units granted at target	43,871	58,902
Weighted average grant date fair value per share	$ 45.59	$ 36.76
Aggregate grant date fair value	$ 2,000	$ 2,165
Stock units forfeited	0	0
Requisite service period	36 months
Minimum [Member]
Share-Based Compensation and Capital Stock [Line Items]
Requisite service period		22 months
Maximum [Member]
Share-Based Compensation and Capital Stock [Line Items]
Requisite service period		36 months