Securities Financing Activities (Details) - USD ($) $ in Thousands		Sep. 30, 2020	Dec. 31, 2019
Securities purchased under agreements to resell
Securities purchased under agreements to resell, subject to master netting arrangement, gross amounts recognized		$ 3,616,312	$ 656,504
Securities purchased under agreements to resell, subject to a master netting arrangement, gross amounts offset in the condensed consolidated balance sheets		3,472,218	477,590
Securities purchased under agreements to resell, subject to a master netting arrangement, net amount presented in the condensed consolidated balance sheets		144,094	178,914
Securities purchased under agreements to resell, subject to a master netting arrangement, financial instruments collateral received/ pledged	[1]	144,094	178,914
Securities purchased under agreements to resell, net amount		0	0
Securities sold under agreements to repurchase
Securities sold under agreements to repurchase, subject to a master netting arrangement, gross amounts recognized		3,661,692	650,618
Securities sold under agreements to repurchase, gross amounts offset in the condensed consolidated balance sheets		3,472,218	477,590
Securities sold under agreements to repurchase, subject to a master netting arrangement, net amount presented in the condensed consolidated balance sheet		189,474	173,028
Securities sold under agreements to repurchase, subject to a master netting arrangement, financial instruments collateral received/ pledged	[1]	189,474	173,028
Securities sold under agreements to repurchase, subject to a master netting arrangement, net amount		0	0
Fair value of collateral received related to securities purchased under agreements to resell		4,300,000	648,000
Fair value of collateral pledged related to securities sold under agreements to repurchase		$ 4,300,000	$ 644,000

[1] The actual amount of collateral received/pledged is limited to the asset/liability balance and does not include excess collateral received/pledged. When excess collateral exists, the collateral shown in the table above has been allocated based on the percentage of the actual amount of collateral posted.