Summary of Significant Accounting Policies (Details) (Interest rate contracts, USD $) In Millions, unless otherwise specified			3 Months Ended
	Mar. 31, 2014 item	Dec. 31, 2013 item	Mar. 31, 2014 Cash Flow Hedging	Mar. 31, 2013 Cash Flow Hedging
Derivative instruments
Number of interest rate swaps held	0	0
Notional amount of outstanding derivative instruments		$ 100.0
Net fair value of swap liability				1.2
Net finance costs			$ (0.1)	$ 0.4