Schedule of the Remaining Contractual Maturity by Collateral Type of Securities Sold Under Agreements To Repurchase (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	$ 451,129	$ 338,133	$ 311,760
U.S. treasuries
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	28,218		15,175
Government agency issued MBS
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	408,861		93,697
Government agency issued CMO
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	14,050		202,888
Overnight and Continuous
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	336,775		299,310
Overnight and Continuous | U.S. treasuries
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	28,218		15,175
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	308,557		93,697
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		190,438
Up to 30 Days
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	14,050		12,450
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	14,050		12,450
30 - 90 Days
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	100,304		0
30 - 90 Days | U.S. treasuries
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	0		0
30 - 90 Days | Government agency issued MBS
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	100,304		0
30 - 90 Days | Government agency issued CMO
Transfer Of Certain Financial Assets Accounted For As Secured Borrowings [Line Items]
Securities sold under agreements to repurchase	$ 0		$ 0