Derivative Financial Instruments Schedule of forward-settle interest rate swaps (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Derivative [Line Items]
Total Notional Amount	$ 10,405,957	$ 13,138,667
Forward Contracts [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Matures June 30, 2019 [Member]
Derivative [Line Items]
Number of Instruments	1
Total Notional Amount	25,000
Forward Contracts [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Matures October 16, 2019 and November 18, 2019 [Member]
Derivative [Line Items]
Number of Instruments	4
Total Notional Amount	100,000
Forward Contracts [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Matures January 31, 2020 [Member]
Derivative [Line Items]
Number of Instruments	2
Total Notional Amount	50,000
Forward Contracts [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Matures June 16, 2020 [Member]
Derivative [Line Items]
Number of Instruments	2
Total Notional Amount	$ 50,000