Fair Value of Financial Instruments (Details 3)	1 Months Ended			39 Months Ended	3 Months Ended
	Dec. 31, 2013 Interest rate swaps USD ($)	Dec. 31, 2012 Interest rate swaps USD ($)	Mar. 31, 2011 Interest rate swaps USD ($) contract	Dec. 31, 2013 Interest rate swaps USD ($)	Dec. 31, 2013 Cross currency swaps USD ($)	Dec. 31, 2013 Cross currency swaps GBP (£)	Dec. 31, 2012 Cross currency swaps USD ($)	Dec. 31, 2010 Cross currency swaps contract
Derivative information
Number of derivative contracts entered into by the entity			3					3
Notional amount of each derivative contract	$ 166,666,000	$ 266,666,000	$ 333,333,000		$ 300,000,000	£ 194,200,000
Notional amount of derivative contracts			1,000,000,000
Fixed interest rate (as a percent)			1.92%
Derivative term			4 years
Forward rate (as a percent)					1.565	1.565
Hedge ineffectiveness (gain)/ loss				$ 0	$ (1,010,000)		$ 64,000