Derivatives Offsetting Assets (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Offsetting Assets [Line Items]
Derivative Asset, Fair Value, Gross Asset		$ 368	$ 28,534
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		368	28,534
Derivative, Collateral, Obligation to Return Securities	[1]	0	(6,449)
Derivative, Collateral, Obligation to Return Cash		0	22,085	[1]
Derivative Asset, Fair Value, Amount Offset Against Collateral		368	0
Interest Rate Swap
Offsetting Assets [Line Items]
Derivative Asset, Fair Value, Gross Asset		368	28,534
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		368	28,534
Derivative, Collateral, Obligation to Return Securities	[1]	0	(6,449)
Derivative, Collateral, Obligation to Return Cash		0	(22,085)
Derivative Asset, Fair Value, Amount Offset Against Collateral		$ 368	$ 0

[1] Amounts disclosed for collateral received by or posted to the same counterparty include cash and the fair value of MBS up to and not exceeding the net amount of the asset or liability presented in the balance sheet. The fair value of the actual collateral received by or posted to the same counterparty may exceed the amounts presented.