Derivative and Hedging Activities (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Interest Rate Swaps
Notional Amount	$ 325.0
Fair Value	(4.0)
Interest Rate Swap Notional $50 Million Maturing March 2013
Interest Rate Swaps
Notional Amount	50.0
Derivative Maturity Period	March 2013
Variable Rate	1 Month LIBOR
Fixed Rate	0.72%
Fair Value	(0.1)
Interest Rate Swap Notional $50 Million Maturing June 2013
Interest Rate Swaps
Notional Amount	50.0
Derivative Maturity Period	June 2013
Variable Rate	1 Month LIBOR
Fixed Rate	0.84%
Fair Value	(0.1)
Interest Rate Swap Notional $225 Million Maturing July 2014
Interest Rate Swaps
Notional Amount	225.0
Derivative Maturity Period	July 2014
Variable Rate	1 Month LIBOR
Fixed Rate	1.37%
Fair Value	$ (3.8)