Derivatives (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Interest Expense:
Hedge ineffectiveness (gains) losses	$ 128	$ (1,519)
Amortization:
Amortization of loss of designated interest rate derivative	341	0
Amortization of deferred losses	7,933	4,071
Total Amortization	8,274	4,071
Total charged to interest expense	8,402	2,552
Other Income (Expense):
Mark to market (losses) gains on undesignated interest rate derivatives	1,215	(113)
Total charged to other income (expense)	$ 1,215	$ (113)