Fair Value Measurements Fair Value Measurements (Details 3) (Covered Private Label Collateralized Mortgage Obligations Member [Domain], Fair Value, Measurements, Recurring [Member], Level 3, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014
Covered Private Label Collateralized Mortgage Obligations Member [Domain] | Fair Value, Measurements, Recurring [Member] | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings	$ 1,627	$ 1,938	$ 340
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	(344)	(1,204)	4,883
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(5,240)	(7,514)	(5,688)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	$ 37,904	$ 44,684	$ 45,149	$ 33,947