Fair Value Measurements (Effect of Fair Value Measured Assets and Liabilities on Consolidated Statements of Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized gain (loss) on derivatives	$ (70)	$ (817)	$ (680)	$ (7,177)
Unrealized gain (loss) on marketable securities	(2,875)	257	(3,818)	2,039
Credit Default Swaps [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized gain (loss) on derivatives	86	(689)	(331)	(820)
Derivative Assets [Member] | Credit Default Swaps [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Assets			(394)	(886)
Reclassified from Accumulated OCI into Interest Expense, Assets			0	0
Interest Savings (Cost) [Member] | Derivative Assets [Member] | Credit Default Swaps [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Assets			0	0
Fair Value Measurements Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Liabilities	(504)	(327)	855	(5,344)
Unrealized gain (loss) on derivatives	(70)	(817)	(680)	(7,177)
Unrealized gain (loss) on marketable securities	(2,875)	257	(3,818)	2,039
Realized gain (loss) on marketable securities	2,441	233	5,353	(206)
Gain or (Loss) Recognized in income, Net	(504)	(327)	855	(5,344)
Reclassified from Accumulated OCI into Interest Expense, Liabilities	0	29	100	53
Reclassified from Accumulated OCI into Interest Expense, Net	0	29	100	53
Fair Value Measurements Recurring [Member] | Interest Rate Derivatives [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized gain (loss) on derivatives	(156)	(128)	(349)	(6,357)
Reclassified from Accumulated OCI into Interest Expense, Net	0	29	100	53
Fair Value Measurements Recurring [Member] | Credit Default Swaps [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized gain (loss) on derivatives	86	(689)	(331)	(820)
Reclassified from Accumulated OCI into Interest Expense, Net	0	0	0	0
Fair Value Measurements Recurring [Member] | Derivative Liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Liabilities	314	168
Reclassified from Accumulated OCI into Interest Expense, Liabilities	0	0
Fair Value Measurements Recurring [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Liabilities			0	4,400
Reclassified from Accumulated OCI into Interest Expense, Liabilities			0	0
Fair Value Measurements Recurring [Member] | Derivative Liabilities [Member] | Credit Default Swaps [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Liabilities			0	(142)
Reclassified from Accumulated OCI into Interest Expense, Liabilities			0	0
Fair Value Measurements Recurring [Member] | Derivative Liabilities [Member] | Put Option [Member] | Short [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Liabilities	102	(148)	46	0
Reclassified from Accumulated OCI into Interest Expense, Liabilities	0	0	0	0
Fair Value Measurements Recurring [Member] | Derivative Liabilities [Member] | Call Option [Member] | Short [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Liabilities	212	316	235	402
Reclassified from Accumulated OCI into Interest Expense, Liabilities	0	0	0	0
Fair Value Measurements Recurring [Member] | Non-Derivative Liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Liabilities			281	4,660
Reclassified from Accumulated OCI into Interest Expense, Liabilities			0	0
Fair Value Measurements Recurring [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Assets	(156)	(128)	(349)	(10,757)
Reclassified from Accumulated OCI into Interest Expense, Assets	0	29	100	53
Fair Value Measurements Recurring [Member] | Derivative Assets [Member] | Put and Call Options [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Assets	(115)	(621)	(1,219)	(435)
Reclassified from Accumulated OCI into Interest Expense, Assets	0	0	0	0
Fair Value Measurements Recurring [Member] | Derivative Assets [Member] | Credit Default Swaps [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Assets	65	(711)
Reclassified from Accumulated OCI into Interest Expense, Assets	0	0
Fair Value Measurements Recurring [Member] | Non Derivative Assets [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Assets	(818)	(495)	574	(10,004)
Reclassified from Accumulated OCI into Interest Expense, Assets	0	29	100	53
Fair Value Measurements Recurring [Member] | Non Derivative Assets [Member] | Equity and U.S Treasury Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Assets	(612)	965	2,536	2,074
Reclassified from Accumulated OCI into Interest Expense, Assets	0	0	0	0
Fair Value Measurements Recurring [Member] | Interest Savings (Cost) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Liabilities			0	6,215
Unrealized gain (loss) on derivatives			0	6,215
Unrealized gain (loss) on marketable securities			0	0
Realized gain (loss) on marketable securities			0	0
Gain or (Loss) Recognized in income, Net			0	6,215
Fair Value Measurements Recurring [Member] | Interest Savings (Cost) [Member] | Interest Rate Derivatives [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized gain (loss) on derivatives			0	6,215
Fair Value Measurements Recurring [Member] | Interest Savings (Cost) [Member] | Credit Default Swaps [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized gain (loss) on derivatives			0	0
Fair Value Measurements Recurring [Member] | Interest Savings (Cost) [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Liabilities			0	(4,424)
Fair Value Measurements Recurring [Member] | Interest Savings (Cost) [Member] | Derivative Liabilities [Member] | Credit Default Swaps [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Liabilities			0	0
Fair Value Measurements Recurring [Member] | Interest Savings (Cost) [Member] | Derivative Liabilities [Member] | Put Option [Member] | Short [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Liabilities			0	0
Fair Value Measurements Recurring [Member] | Interest Savings (Cost) [Member] | Derivative Liabilities [Member] | Call Option [Member] | Short [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Liabilities			0	0
Fair Value Measurements Recurring [Member] | Interest Savings (Cost) [Member] | Non-Derivative Liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Liabilities			0	(4,424)
Fair Value Measurements Recurring [Member] | Interest Savings (Cost) [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Assets			0	10,639
Fair Value Measurements Recurring [Member] | Interest Savings (Cost) [Member] | Derivative Assets [Member] | Put and Call Options [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Assets			0	0
Fair Value Measurements Recurring [Member] | Interest Savings (Cost) [Member] | Non Derivative Assets [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Assets			0	10,639
Fair Value Measurements Recurring [Member] | Interest Savings (Cost) [Member] | Non Derivative Assets [Member] | Equity and U.S Treasury Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain or (Loss) Recognized in income, Assets			$ 0	$ 0