Stock Compensation Plans (Details 3) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2012
Summary of stock compensation awards outstanding and exercisable
Number of Awards outstanding, Ending balance (in shares)	1,633,405
Weighted Average Exercise Price Awards outstanding, Ending balance (in dollars per share)	$ 26.22
Intrinsic Value Awards outstanding, Ending balance	$ 7.3
Weighted Average Remaining Contractual Life Awards outstanding, Ending balance	6 years 3 months 15 days
Number of Awards exercisable, Ending balance (in shares)	898,793
Weighted Average Exercise Price Awards exercisable, Ending balance (in dollars per share)	$ 23.82
Intrinsic Value Awards exercisable, Ending balance	$ 6.2
Weighted Average Remaining Contractual Life Awards exercisable, Ending balance	4 years 5 months 16 days