Share-Based Compensation and Capital Stock Summary Of Activity Related To Restricted Stock Grants (Details) (Restricted Stock [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
Granted - shares	7,646	7,672	223,045	266,159
Weighted average grant date fair value per share	$ 39.24	$ 32.59	$ 37.65	$ 35.76
Aggregate grant date fair value	$ 300	$ 250	$ 8,397	$ 9,517
Restricted shares forfeited	25	13,619	27,953	23,921
Vesting service period of shares granted	36 months	36 months
Grant date fair value of shares vested	$ 94	$ 75	$ 8,569	$ 6,693
Minimum [Member]
Vesting service period of shares granted			12 months	12 months
Maximum [Member]
Vesting service period of shares granted			48 months	68 months