Master Netting and Similar Agreements—Repurchase, Reverse Repurchase, and Securities Borrowing Transactions - Securities Sold Under Agreements To Repurchase And Collateral Pledged By Company (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Securities Sold under Agreements to Repurchase [Abstract]
Gross amounts of recognized liabilities	$ 745,788	$ 762,592
Gross amounts offset in the Statements of Condition	0	0
Net amounts of liabilities presented in the Statements of Condition	745,788	762,592
Offsetting securities purchased under agreements to resell	(1,276)	(261)
Securities/ government guaranteed loans collateral	(744,427)	(762,322)
Net amount	$ 85	$ 9