Share-Based Compensation and Capital Stock Summary of Change in Stock-Based Award Activity (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2012
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at January 1, 2013 - Shares			1,934,034
Granted - Shares			173,413
Exercised - Shares	(29,008)	(109,996)	(263,073)		(135,200)
Expired - Shares			(75,473)
Forfeited - Shares			0
Outstanding at September 30, 2013 - Shares	1,768,901		1,768,901
Options exercisable at September 30, 2013 - Shares	1,265,481		1,265,481
Outstanding at January 1, 2013 - Weighted average exercise price			$ 25.80
Granted - Weighted average exercise price			$ 36.76
Exercised - Weighted average exercise price			$ 25.38
Expired - weighted average exercise price			$ 36.99
Forfeited - Weighted average exercise price			$ 0
Outstanding at September 30, 2013 - Weighted average exercise price	$ 26.46		$ 26.46
Options exercisable at September 30, 2013 - Weighted average exercise price	$ 24.70		$ 24.70
Weighted Average Remaining Contractual Term - Options Outstanding at September 30, 2013			3 years 2 months 12 days
Weighted Average Remaining Contractual Term - Options Exercisable at September 30, 2013			2 years 4 months 24 days
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Outstanding at January 1, 2013 - Shares			606,547
Granted - shares	7,646	7,672	223,045		266,159
Vested - Shares			(227,890)
Forfeited - Shares	(25)	(13,619)	(27,953)		(23,921)
Outstanding at September 30, 2013 - Shares	573,749		573,749
Outstanding at January 1, 2013 - Weighted average grant date fair value			$ 35.17
Granted - Weighted average grant date fair value	$ 39.24	$ 32.59	$ 37.65		$ 35.76
Vested - Weighted average grant date fair value			$ 33.94
Forfeited - Weighted average grant date fair value			$ 35.30
Outstanding at September 30, 2013 - Weighted average grant date fair value	$ 36.61		$ 36.61
Performance Vested Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Outstanding at January 1, 2013 - Shares			170,116
Granted - shares	0	6,137	58,902		100,046
Performance based leveraging - shares			9,192	[1]
Vested - Shares	0	0	(39,816)
Forfeited - Shares	0	0	0		(57,176)
Outstanding at September 30, 2013 - Shares	198,394		198,394
Outstanding at January 1, 2013 - Weighted average grant date fair value			$ 35.56
Granted - Weighted average grant date fair value		$ 32.59	$ 36.76		$ 35.68
Performance based leveraging - Weighted average grant date fair value			$ 32.60	[1]
Vested - Weighted average grant date fair value			$ 32.60
Forfeited - Weighted average grant date fair value			$ 0
Outstanding at September 30, 2013 - Weighted average grant date fair value	$ 36.37		$ 36.37

[1] PVRSU shares have been increased by 9,192 units due to the Company exceeding the targeted performance conditions contained in PVRSUs granted in prior periods during the nine months ended September 30, 2013.