Repurchase Agreements (Tables)

12 Months Ended

Dec. 31, 2017

Repurchase Agreements [Abstract]

Schedule of Repurchase Agreements [Table Text Block]

The remaining contractual maturity of the securities sold under agreements to repurchase by class of collateral pledged included in borrowings on the Consolidated Balance Sheets as of December 31, 2017 and December 31, 2016 is presented in the following tables.

	December 31, 2017
	Remaining Contractual Maturity of the Agreements
(Dollars in thousands)	Overnight and continuous		Up to 30 Days		30-90 Days		Greater than 90 Days		Total
Repurchase agreements
U.S. Treasury	$	556,171	$	—	$	30,000	$	—	$	586,171
Gross amount of recognized liabilities for repurchase agreements									$	586,171
	December 31, 2016
	Remaining Contractual Maturity of the Agreements
	Overnight and continuous		Up to 30 Days		30-90 Days		Greater than 90 Days		Total
Repurchase agreements
U.S. Treasury	$	590,772	$	—	$	—	$	30,000	$	620,772
Gross amount of recognized liabilities for repurchase agreements									$	620,772