Balance Sheet Offsetting Offsetting Assets & Liabilities (Table) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Balance Sheet Offsetting [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	$ 12,268	$ 12,980
Derivative Asset, Amount Offset	0	0
Derivative Assets	12,268	12,980
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	12,642	13,329
Derivative Liability, Amount Offset	0	0
Derivative Liabilities	12,642	13,329
Resale agreement [Member]
Balance Sheet Offsetting [Line Items]
Securities Purchased under Agreements to Resell, Gross	1,350,000	1,450,000
Securities Purchased under Agreements to Resell, Liability	(400,000)	(300,000)
Securities Purchased under Agreements to Resell	950,000	1,150,000
Securities Purchased under Agreements to Resell, Not Subject to Master Netting Arrangement	0	0
Securities Purchased under Agreements to Resell, Collateral, Obligation to Return Securities	(950,000)	(1,150,000)
Securities Purchased under Agreements to Resell, Amount Offset Against Collateral	0	0
Derivative Subject to Master Netting Agreement [Member]
Balance Sheet Offsetting [Line Items]
Derivative Asset, Fair Value, Gross Asset	11,569	11,579
Derivative Asset, Fair Value, Gross Liability	0	0
Derivative Asset, Fair Value, Net	11,569	11,579
Derivative Asset, Not Offset, Policy Election Deduction	(367)	(1,299)
Derivate Asset, Fair Value of Collateral	0	(338)
Derivative Asset, Fair Value, Amount Offset Against Collateral	11,202	9,942
Derivative Liability, Fair Value, Gross Liability	12,568	12,962
Derivative Liability, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Net	12,568	12,962
Derivative Liability, Not Offset, Policy Election Deduction	(367)	(1,299)
Derivative Liability, Fair Value of Collateral	(10,554)	(9,063)
Derivative Liability, Fair Value, Amount Offset Against Collateral	1,647	2,600
Derivative Not Subject to Master Netting Agreement [Member]
Balance Sheet Offsetting [Line Items]
Derivative Asset, Fair Value, Gross Asset	699	1,401
Derivative Asset, Fair Value, Gross Liability	0	0
Derivative Asset, Not Subject to Master Netting Arrangement	699	1,401
Derivative Liability, Fair Value, Gross Liability	74	367
Derivative Liability, Fair Value, Gross Asset	0	0
Derivative Liability, Not Subject to Master Netting Arrangement	74	367
Repurchase agreement [Member]
Balance Sheet Offsetting [Line Items]
Securities Sold under Agreements to Repurchase, Gross	1,378,678	1,621,763
Securities Sold under Agreements to Repurchase, Asset	(400,000)	(300,000)
Securities Sold under Agreements to Repurchase	978,678	1,321,763
Securities Sold under Agreements to Repurchase, Not Subject to Master Netting Arrangement	0	0
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Securities	(978,678)	(1,321,763)
Securities Sold under Agreements to Repurchase, Amount Offset Against Collateral	$ 0	$ 0