Borrowing Arrangements (Details 6) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Debt Disclosure [Abstract]
Unamortized fair value adjustment related to long-term debt	$ 111.6
Estimated aggregate amortization of the fair value adjustment	52.3
Estimated aggregate amortization of fair value adjustment related to long-term debt (reduction of interest expense) for each of the next five years:
2013	34.1
2014	28.2
2015	15.6
2016	8.9
2017	$ 5.3