Share-Based Compensation and Capital Stock Summary of Change in Stock-Based Award Activity (Details) (USD $)	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, beginning balance - Shares	1,903,177
Granted - Shares	498,911		700,000
Exercised - Shares	(228,963)		(58,749)
Expired - Shares	0
Forfeited - Shares	(3,685)
Outstanding, ending balance - Shares	2,169,440		2,300,000
Options exercisable, ending balance - Shares	1,057,276
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Outstanding, beginning balance - Weighted average exercise price (in dollars per share)	$ 33.03
Granted - Weighted average exercise price (in dollars per share)	$ 63.47
Exercised - Weighted average exercise price (in dollars per share)	$ 24.54
Expired - Weighted average exercise price (in dollars per share)	$ 0.00
Forfeited - Weighted average exercise price (in dollars per share)	$ 45.59
Outstanding, ending balance - Weighted average exercise price (in dollars per share)	$ 40.91
Options Exercisable, ending balance - Weighted average exercise price (in dollars per share)	$ 29.08
Share-based Compensation Arrangement by Share-based Payment Award, Options, Weighted Average Remaining Contractual Term [Roll Forward]
Weighted Average Remaining Contractual Term - Outstanding, ending balance	4 years 7 months 6 days
Weighted Average Remaining Contractual Term - Options Exercisable, ending balance	2 years 10 months 24 days
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Outstanding, beginning balance - Shares	479,556
Granted - shares	85,792		129,793
Vested - Shares	(172,165)
Forfeited - Shares	(4,778)		(1,332)
Outstanding, ending balance - Shares	388,405
Outstanding, beginning balance - Weighted average grant date fair value (in dollars per share)	$ 40.14
Granted - Weighted average grant date fair value (in dollars per share)	$ 63.46		46.71
Vested - Weighted average grant date fair value (in dollars per share)	$ 38.82
Forfeited - Weighted average grant date fair value (in dollars per share)	$ 39.89
Outstanding, ending balance - Weighted average grant date fair value (in dollars per share)	$ 45.88
Performance Vested Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Outstanding, beginning balance - Shares	200,286
Granted - shares	30,353		43,871
Performance-based leveraging - Shares	3,850	[1]	10,251
Vested - Shares	(42,326)		(28,886)
Forfeited - Shares	0		0
Outstanding, ending balance - Shares	192,163
Outstanding, beginning balance - Weighted average grant date fair value (in dollars per share)	$ 38.28
Granted - Weighted average grant date fair value (in dollars per share)	$ 63.47		45.59
Performance-Based Leveraging - Weighted average grant date fair value (in dollars per share)	$ 35.60
Vested - Weighted average grant date fair value (in dollars per share)	$ 35.60
Forfeited - Weighted average grant date fair value (in dollars per share)	$ 0.00
Outstanding, ending balance - Weighted average grant date fair value (in dollars per share)	$ 42.79

[1] PVRSU units outstanding have been increased by 3,850 units due to the Company exceeding the targeted performance conditions contained in PVRSUs granted in prior periods during the three months ended March 31, 2015.