Derivative Financial Instruments Derivative Financial Instruments (Details 3) (Interest Rate Swap [Member], USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
March 15, 2013 Interest rate swap [Member]
Derivative [Line Items]
Contract date	Mar. 15, 2013
Notional amount	$ 73.1
Fixed rate	1.0165%
Effective date	Apr. 05, 2013
Maturity date	Mar. 31, 2019
March 29, 2013 Interest rate swap [Member]
Derivative [Line Items]
Contract date	Mar. 29, 2013
Notional amount	$ 73.1
Fixed rate	0.97%
Effective date	Apr. 05, 2013
Maturity date	Mar. 31, 2019