Share-Based Compensation and Capital Stock Summary of Change in Stock-Based Award Activity (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014		Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at January 1, 2014 - Shares			1,661,952
Granted - Shares	0	0	651,757		200,000
Exercised - Shares	0	(29,742)	(58,749)		(234,065)
Expired - Shares			0
Forfeited - Shares			0
Outstanding at June 30, 2014 - Shares	2,254,960	1,800,000	2,254,960		1,800,000
Options Exercisable at June 30, 2014 - Shares	1,326,714		1,326,714
Outstanding at January 1, 2014 - Weighted average exercise price (in dollars per share)			$ 26.44
Granted - Weighted average exercise price (in dollars per share)			$ 45.59
Exercised - Weighted average exercise price (in dollars per share)			$ 26.33
Expired - weighted average exercise price (in dollars per share)			$ 0.00
Forfeited - Weighted average exercise price (in dollars per share)			$ 0.00
Outstanding at June 30, 2014 - Weighted average exercise price (in dollars per share)	$ 31.98		$ 31.98
Options Exercisable at June 30, 2014 - Weighted average exercise price (in dollars per share)	$ 25.24		$ 25.24
Weighted Average Remaining Contractual Term - Outstanding at June 30, 2014			3 years 8 months 12 days
Weighted Average Remaining Contractual Term - Options Exercisable at June 30, 2014			2 years 1 month 6 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, 2014 - Shares			563,345
Restricted share grants	17,262	20,858	147,055		215,399
Vested - Shares			(172,997)
Forfeited - Shares	(2,964)	(6,429)	(4,296)		(27,928)
Outstanding at June 30, 2014 - Shares	533,107		533,107
Outstanding at January 1, 2014 - Weighted average grant date fair value (in dollars per share)			$ 36.64
Granted - Weighted average grant date fair value (in dollars per share)	$ 44.62	$ 45.32	$ 46.46		$ 37.59
Vested - Weighted average grant date fair value (in dollars per share)			$ 37.04
Forfeited - Weighted average grant date fair value (in dollars per share)			$ 39.18
Outstanding at June 30, 2014 - Weighted average grant date fair value (in dollars per share)	$ 39.20		$ 39.20
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, 2014 - Shares			216,342
Restricted share grants	0	0	24,678		58,902
Performance-Based Leveraging - Shares			10,251	[1]	9,192	[1]
Vested - Shares	0	0	(28,886)		(39,816)
Forfeited - Shares	0	0	0		0
Outstanding at June 30, 2014 - Shares	222,385		222,385
Outstanding at January 1, 2014 - Weighted average grant date fair value (in dollars per share)			$ 37.34
Granted - Weighted average grant date fair value (in dollars per share)			$ 45.59		$ 36.76
Performance-Based Leveraging - Weighted average grant date fair value (in dollars per share)			$ 41.25	[1]
Vested - Weighted average grant date fair value (in dollars per share)			$ 41.25
Forfeited - Weighted average grant date fair value (in dollars per share)			$ 0.00
Outstanding at June 30, 2014 - Weighted average grant date fair value (in dollars per share)	$ 37.93		$ 37.93

[1] PVRSU units outstanding have been increased by 10,251 units due to the Company exceeding the targeted performance conditions contained in PVRSUs granted in prior periods during the six months ended June 30, 2014.