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, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Granted - shares	7,672	45,674	266,159	247,298
Weighted average grant date fair value per share	$ 32.59	$ 30.27	$ 35.76	$ 38.84
Aggregate grant date fair value ($000)	$ 250	$ 1,383	$ 9,517	$ 9,604
Restricted shares forfeited	13,619	5,884	23,921	33,252
Vesting service period of shares granted	36 months	36 months
Grant date fair value of shares vested ($000)	$ 75	$ 298	$ 6,693	$ 6,655
Minimum [Member]
Vesting service period of shares granted			12 months	12 months
Maximum [Member]
Vesting service period of shares granted			68 months	48 months