Schedule of the Remaining Contractual Maturity by Collateral Type of Securities Sold Under Agreements To Repurchase (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	$ 341,998	$ 338,133	$ 332,329
U.S. treasuries
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	38,382		23,812
Government agency issued MBS
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	289,341
Government agency issued CMO
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	14,275		308,517
Overnight and Continuous
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	327,723		321,390
Overnight and Continuous | U.S. treasuries
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	38,382		23,812
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	289,341
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		297,578
Up to 30 Days
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	14,275		10,939
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		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	$ 14,275		$ 10,939