Financing Arrangements (Details Textual) (USD $) In Millions, unless otherwise specified			6 Months Ended													6 Months Ended			6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 Series A Medium Term Note [Member]	Dec. 31, 2011 Series A Medium Term Note [Member]	Jun. 30, 2012 Senior Unsecured Notes [Member]	Dec. 31, 2011 Senior Unsecured Notes [Member]	Jun. 30, 2012 Ohio Water Development Revenue Refunding Bonds [Member]	Dec. 31, 2011 Ohio Water Development Revenue Refunding Bonds [Member]	Jun. 30, 2012 Ohio Air Quality Development Revenue Refunding Bonds [Member]	Dec. 31, 2011 Ohio Air Quality Development Revenue Refunding Bonds [Member]	Jun. 30, 2012 Ohio Pollution Control Revenue Refunding Bonds [Member]	Dec. 31, 2011 Ohio Pollution Control Revenue Refunding Bonds [Member]	Jun. 30, 2012 Credit Facility with US Bank for AGC [Member]	Dec. 31, 2011 Credit Facility with US Bank for AGC [Member]	Jun. 30, 2012 Foreign Subsidiary [Member]	Jun. 30, 2012 Line of Credit Accounts Receivable Securitization [Member]	Jun. 30, 2012 Senior Credit Facility [Member]	May 11, 2011 Senior Credit Facility [Member]	Jun. 30, 2012 Amended Senior Credit Facility [Member]	Jun. 30, 2012 Senior Credit Facility Letters of Credit [Member]	Jun. 30, 2012 Foreign Subsidiary Long Term Borrowings [Member]	Jun. 30, 2012 Variable Rate Lines of Credit [Member]	Dec. 31, 2011 Variable Rate Lines of Credit [Member]
Financing Arrangements (Textual) [Abstract]
Maximum borrowing capacity under line of credit															$ 239.0	$ 150.0		$ 500.0			$ 18.9
Borrowings outstanding															8.1	0	0			17.2	18.9
Borrowings guarantees															3.4
Remaining Borrowing Capacity under Line of Credit Facility of Company's foreign subsidiaries															227.5		482.8
Line of credit stated variable interest rate, Low Range																						2.49%	2.24%
Line of Credit stated variable interest rate, High Range																						6.89%	11.00%
Line of credit expiration date																November 10, 2012			May 11, 2016
Total Long-term debt	$ 486.1	$ 493.1	$ 175.0	$ 175.0	$ 249.8	$ 249.8	$ 12.2	$ 12.2	$ 9.5	$ 9.5	$ 17.0	$ 17.0	$ 1.7	$ 5.1
Number of Financial Covenant under senior Credit Facility																	2
Debt Instrument, Interest rate					6.00%		0.19%		0.39%		0.39%		1.35%
Fixed-rate Medium-Term Notes, Series A, Interest rate, Minimum			6.74%
Fixed-rate Medium-Term Notes, Series A, Interest rate, Maximum			7.76%
Debt Instruments, Maturity Date			May 01, 2028		Sep. 15, 2014		Nov. 01, 2025		Nov. 01, 2025		Jun. 01, 2033		May 23, 2013