Schedule of the Remaining Contractual Maturity by Collateral Type of Securities Sold Under Agreements To Repurchase (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	$ 406,354	$ 453,053
U.S. treasuries
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	19,344	14,864
Government agency issued MBS
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	345,156	421,771
Government agency issued CMO
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	41,854	16,418
Overnight and Continuous
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	393,883	436,635
Overnight and Continuous | U.S. treasuries
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	19,344	14,864
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	345,156	421,771
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	29,383	0
Up to 30 Days
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	12,471	16,418
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	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	$ 12,471	$ 16,418