Securities Financing Activities (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Securities purchased under agreements to resell
Securities purchased under agreements to resell, subject to master netting arrangement, gross amounts recognized		$ 2,888,149	$ 3,164,039
Securities purchased under agreements to resell, subject to a master netting arrangement, gross amounts offset in the condensed consolidated balance sheets		2,746,902	3,069,489
Securities purchased under agreements to resell, subject to a master netting arrangement, net amount presented in the condensed consolidated balance sheets		141,247	94,550
Securities purchased under agreements to resell, subject to a master netting arrangement, financial instruments collateral received/ pledged	[1]	141,247	94,550
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		2,818,461	3,095,655
Securities sold under agreements to repurchase, gross amounts offset in the condensed consolidated balance sheets		2,746,902	3,069,488
Securities sold under agreements to repurchase, subject to a master netting arrangement, net amount presented in the condensed consolidated balance sheet		71,559	26,167
Securities sold under agreements to repurchase, subject to a master netting arrangement, financial instruments collateral received/ pledged	[1]	71,559	26,167
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		3,200,000	3,100,000
Fair value of collateral pledged related to securities sold under agreements to repurchase		$ 2,800,000	$ 3,100,000

[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.