Derivative Instruments (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Derivatives
Fair value of derivative assets, Swaps	$ 13,000		$ 203
Hedging
Derivatives
Fair value of derivative assets, Swaps	13,000		203
Fair value of derivative liabilities, Swaps	(28,217)	[1]	(63,034)	[1]
Linked Transactions | Non-Hedging | Assets
Derivatives
Linked Transactions	28,181		12,704
Swaps | Hedging | Assets | Non-cleared legacy swaps
Derivatives
Notional amount of derivative assets, Swaps	450,000	[2]
Fair value of derivative assets, Swaps	4,925	[2]	203	[2]
Swaps | Hedging | Assets | Cleared swaps
Derivatives
Notional amount of derivative assets, Swaps	1,300,000	[3]
Fair value of derivative assets, Swaps	8,075	[3]	0	[3]
Swaps | Hedging | Liability | Non-cleared legacy swaps
Derivatives
Notional amount of derivative liabilities, Swaps	1,445,212	[2]
Fair value of derivative liabilities, Swaps	(24,437)	[2]	(63,034)	[2]
Swaps | Hedging | Liability | Cleared swaps
Derivatives
Notional amount of derivative liabilities, Swaps	850,000	[3]
Fair value of derivative liabilities, Swaps	$ (3,780)	[3]	$ 0	[3]

[1] The fair value of securities pledged against the Company’s Swaps was $73.9 million and $68.9 million at December 31, 2013 and 2012, respectively.

[2] Non-cleared legacy Swaps include Swaps executed and settled bilaterally with counterparties without the use of an organized exchange or central clearing house.

[3] Cleared Swaps include Swaps executed bilaterally with a counterparty in the over-the-counter market but then novated to a central clearing house, whereby the central clearing house becomes the counterparty to both of the original counterparties.