Share-Based Compensation Plans Share-Based Compensation Plans - Activity of Stock Options Exercisable and Outstanding (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest [Abstract]
Exercisable and vested options at period end, shares under option	10
Exercisable and vested options at period end, remaining contractual life (in years)	3 years 2 months
Exercisable and vested options at period end, average exercise price per share	$ 48.63
Exercisable and vested options at period end, intrinsic value per share	$ 46.67	[1]
Exercisable and vested options at period end, aggregate intrinsic value	$ 483
Common Stock, Market Fair Value	$ 95.30

[1] Computed based upon the amount by which the fair market value of the Company’s common stock at December 31, 2014 of $95.30 per share exceeded the weighted average exercise price.