Fair Value (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended				9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Non-Designated Hedges derivative		Sep. 30, 2014 Cash Flow Hedges derivative		Dec. 31, 2013 Interest Rate Contract [Member]
Derivative instruments and Hedging Activities
Notional balance					$ 606,274		$ 171,302		$ 215,000
Weighted average interest rate (as a percent)					1.70%	[1]	2.50%	[1]
Weighted average capped interest rate (as a percent)					5.90%		5.10%
Number of derivative instruments held					14		4
Hedging losses reclassified from accumulated other comprehensive income into earnings	1,546	54,948	4,557	57,913
Estimated hedging losses to be reclassified from accumulated other comprehensive loss into earnings within the next twelve months							5,493
Gain (Loss) on Interest Rate Fair Value Hedge Ineffectiveness	$ 0	$ (53,484)	$ 0	$ (51,000)

[1] Represents the weighted average interest rate on the hedged debt.