Fair Value Disclosure (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Fair Value Disclosure (Textual) [Abstract]
Aggregate notional amount of outstanding Fair value hedge derivative instruments	$ 350.0	$ 350.0
Aggregate notional amount of outstanding Cash flow hedge derivative instruments	72.9	73.4
Aggregate fair value of all derivative instruments with Net liability position	2.6
Expected Pre tax reclassification of net losses from accumulated other comprehensive income to earnings in Next Twelve Months	6.9
Expected After tax reclassification of net losses from accumulated other comprehensive income to earnings in Next Twelve Months	$ 4.4
Fair Value Hedging [Member]
Derivative (Textual) [Abstract]
No. of instruments, outstanding	3	3
Maturity date range of hedge derivatives	2012-2015
Cash Flow Hedging [Member]
Derivative (Textual) [Abstract]
No. of instruments, outstanding	11	11
Maturity date range of hedge derivatives	2012-2014