Stock-Based Compensation Plans (Details 4) (Employee Stock Purchase Plan, USD $) Share data in Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Employee Stock Purchase Plan
Stock-Based Compensation Plans - Disclosures
Maximum value of company common stock that can be purchased by an employee per year	$ 25,000
Employee purchase price as a percent of fair market value (as a percent)	85.00%
Share purchases under employee stock purchase plan (in shares)	0.8	0.9	0.7
Weighted-average fair value of discount on employee stock purchase plan (in dollars per share)	$ 14.20	$ 5.34	$ 4.20
Intrinsic value from shares settled	11,400,000	4,600,000	3,100,000
Cash received from shares issued	20,400,000	17,800,000	18,700,000
Tax benefits realized from the settlement of share-based payment arrangements	$ 1,100,000	$ 500,000	$ 700,000
Shares available to be issued under employee stock purchase plan (in shares)	5.2