Stock-Based Compensation Plans (Details 5) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Summary of stock option activities
Options exercisable	1,997,969	2,348,469
Number of options, Beginning Balance	2,910,269
Options exercised	(546,408)
Options forfeited	(4,735)
Number of options, Ending Balance	2,359,126
Weighted Average Exercise Price, Beginning Balance	$ 40.33
Weighted Average Exercise Price of Options exercised	$ 30.37
Weighted Average Exercise Price of forfeited	$ 71.21
Weighted Average Exercise Price, Ending Balance	$ 42.59