Schedule of the Remaining Contractual Maturity by Collateral Type of Securities Sold Under Agreements To Repurchase (Details) - USD ($)	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	$ 425,217,000	$ 338,133,000	$ 309,297,000
U.S. treasuries
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	54,273,000
Government agency issued MBS
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	366,799,000
Government agency issued CMO
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	4,145,000
Overnight and Continuous
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	421,072,000
Overnight and Continuous | U.S. treasuries
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	54,273,000
Overnight and Continuous | Government agency issued MBS
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	366,799,000
Overnight and Continuous | Government agency issued CMO
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	0
Up to 30 Days
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	4,145,000
Up to 30 Days | U.S. treasuries
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	0
Up to 30 Days | Government agency issued MBS
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	0
Up to 30 Days | Government agency issued CMO
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	$ 4,145,000