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
	Mar. 31, 2014	Mar. 31, 2013
Share-Based Compensation and Capital Stock [Line Items]
Granted - Shares	129,793	194,541
Weighted average grant date fair value per share	$ 46.71	$ 36.76
Aggregate grant date fair value	$ 6,062	$ 7,151
Restricted shares forfeited	1,332	21,499
Vesting service period of shares granted	4 years
Grant date fair value of shares vested	$ 7,269	$ 6,999
Minimum [Member]
Share-Based Compensation and Capital Stock [Line Items]
Vesting service period of shares granted		3 years
Maximum [Member]
Share-Based Compensation and Capital Stock [Line Items]
Vesting service period of shares granted		4 years