Fair Value Disclosure (Details Textual) (USD $)	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Fair Value Disclosure (Textual) [Abstract]
Aggregate notional amount of outstanding Fair value hedge derivative instruments	$ 100,000,000.0	$ 100,000,000.0
Aggregate notional amount of outstanding Cash flow hedge derivative instruments	126,800,000	129,200,000
Cash flow hedge pre-tax loss to be reclassified within twelve months	6,700,000
Expected After tax reclassification of net losses from accumulated other comprehensive income to earnings in Next Twelve Months	4,200,000
Aggregate fair value of all derivative instruments with Net liability position	$ 2,300,000
Fair Value Hedges [Member]
Fair Value Disclosure (Textual) [Abstract]
Number of instruments, outstanding	1	1
Maturity date range of hedge derivatives	2012-2015	2012-2015
Cash Flow Hedges [Member]
Fair Value Disclosure (Textual) [Abstract]
Number of instruments, outstanding	11	12
Maturity date range of hedge derivatives	2013-2019	2013-2019