Borrowings Summary of Repurchase Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Securities Sold Under Agreements to Repurchase
Repurchase Agreements	$ 423,414	$ 397,107
Overnight and Continuous
Securities Sold Under Agreements to Repurchase
Repurchase Agreements	420,967
Up to 30 Days
Securities Sold Under Agreements to Repurchase
Repurchase Agreements	2,447
U.S. government sponsored enterprises
Securities Sold Under Agreements to Repurchase
Repurchase Agreements	12,507
U.S. government sponsored enterprises | Overnight and Continuous
Securities Sold Under Agreements to Repurchase
Repurchase Agreements	12,507
U.S. government sponsored enterprises | Up to 30 Days
Securities Sold Under Agreements to Repurchase
Repurchase Agreements	0
Residential mortgage-backed securities
Securities Sold Under Agreements to Repurchase
Repurchase Agreements	410,907	397,107
Residential mortgage-backed securities | Overnight and Continuous
Securities Sold Under Agreements to Repurchase
Repurchase Agreements	408,460	391,997
Residential mortgage-backed securities | Up to 30 Days
Securities Sold Under Agreements to Repurchase
Repurchase Agreements	$ 2,447	$ 5,110