Stock-Based Compensation Plans (Details) (USD $)	3 Months Ended
	Mar. 31, 2014
Shares
Exercised (in shares)	(84,836)
2009 Plan | Stock Options
Shares
Options outstanding at the beginning of the period (in shares)	501,568
Exercised (in shares)	(37,572)
Options outstanding at the end of the period (in shares)	463,996
Options exercisable at the end of the period (in shares)	285,517
Weighted average exercise price per share
Options outstanding at the beginning of the period (in dollars per share)	$ 120.77
Exercised (in dollars per share)	$ 111.34
Options outstanding at the end of the period (in dollars per share)	$ 121.53
Options exercisable at the end of the period (in dollars per share)	$ 116.32
1994 Plan | Stock Options
Shares
Options outstanding at the beginning of the period (in shares)	691,526
Exercised (in shares)	(47,264)
Forfeited (in shares)	(550)
Options outstanding at the end of the period (in shares)	643,712
Options exercisable at the end of the period (in shares)	643,712
Weighted average exercise price per share
Options outstanding at the beginning of the period (in dollars per share)	$ 106.19
Exercised (in dollars per share)	$ 80.37
Forfeited (in dollars per share)	$ 49.09
Options outstanding at the end of the period (in dollars per share)	$ 108.13
Options exercisable at the end of the period (in dollars per share)	$ 108.13