Balance Sheet Offsetting - Financial Instruments Derivative Assets Liabilities and Resell Agreements Net of Amount Not Offset (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Derivative: Net Amount Recognized	$ 16,265	$ 2,246
Gross Amounts Not Offset, Financial Instruments	(14,824)	(2,243)
Collateral, Financial Assets	(1,360)	0
Financial Assets, Net Amount	81	3
Net Amount Recognized, Resell Agreements	7,898	4,898
Financial Instruments, Resell Agreements	0	0
Collateral, Resell Agreements, Financial Assets	(7,898)	(4,898)
Net Amount, Financial Assets, Resell Agreements	0	0
Net Amount Recognized, Total Financial Assets	24,163	7,144
Collateral, Financial Assets	(9,258)	(4,898)
Net Amount, Financial Assets	81	3
Net Amount Recognized, Derivatives, Financial Liabilities	42,603	74,159
Financial Instruments, Total Derivatives, Financial Liabilities	(14,824)	(2,243)
Collateral, Derivatives, Financial Liabilities	(27,012)	(68,773)
Net Amount, Derivatives, Financial Liabilities	767	3,143
Net Amount Recognized, Repurchase Agreements, Financial Liabilities	668,053	559,461
Financial Instruments, Repurchase Agreements, Financial Liabilities	0	0
Collateral, Repurchase Agreements, Financial Liabilities	(668,053)	(559,461)
Net Amount, Repurchase Agreements, Financial Liabilities	0	0
Net Amount Recognized, Financial Liabilities	710,656	633,620
Collateral, Financial Liabilities	(695,065)	(628,234)
Net Amount, Financial Liabilities	767	3,143
Counterparty A [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Derivative: Net Amount Recognized	3,342	4
Gross Amounts Not Offset, Financial Instruments	(3,342)	(4)
Collateral, Financial Assets	0	0
Financial Assets, Net Amount	0	0
Net Amount Recognized, Derivatives, Financial Liabilities	18,615	33,999
Financial Instruments, Total Derivatives, Financial Liabilities	(3,342)	(4)
Collateral, Derivatives, Financial Liabilities	(15,167)	(33,778)
Net Amount, Derivatives, Financial Liabilities	106	217
Counterparty B [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Derivative: Net Amount Recognized	8,196	2,033
Gross Amounts Not Offset, Financial Instruments	(8,196)	(2,033)
Collateral, Financial Assets	0	0
Financial Assets, Net Amount	0	0
Net Amount Recognized, Derivatives, Financial Liabilities	9,054	14,374
Financial Instruments, Total Derivatives, Financial Liabilities	(8,196)	(2,033)
Collateral, Derivatives, Financial Liabilities	(613)	(11,318)
Net Amount, Derivatives, Financial Liabilities	245	1,023
Counterparty C [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Derivative: Net Amount Recognized	1,187	189
Gross Amounts Not Offset, Financial Instruments	(1,187)	(189)
Collateral, Financial Assets	0	0
Financial Assets, Net Amount	0	0
Net Amount Recognized, Derivatives, Financial Liabilities	10,870	13,807
Financial Instruments, Total Derivatives, Financial Liabilities	(1,187)	(189)
Collateral, Derivatives, Financial Liabilities	(9,683)	(13,618)
Net Amount, Derivatives, Financial Liabilities	0	0
Other Counterparties [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Derivative: Net Amount Recognized	3,540	20
Gross Amounts Not Offset, Financial Instruments	(2,099)	(17)
Collateral, Financial Assets	(1,360)	0
Financial Assets, Net Amount	81	3
Net Amount Recognized, Derivatives, Financial Liabilities	4,064	11,979
Financial Instruments, Total Derivatives, Financial Liabilities	(2,099)	(17)
Collateral, Derivatives, Financial Liabilities	(1,549)	(10,059)
Net Amount, Derivatives, Financial Liabilities	$ 416	$ 1,903