Securities - Trading Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Schedule of fair value of trading securities
Debt Securities, Trading	$ 648,037	$ 689,576
Investment-related Liabilities
Securities sold, not yet purchased, at fair value	55,340	43,817
US Treasury Securities
Schedule of fair value of trading securities
Debt Securities, Trading	50,487
Bonds
Schedule of fair value of trading securities
Debt Securities, Trading	33,115	24,680
Residential Mortgage Backed Securities
Schedule of fair value of trading securities
Debt Securities, Trading	135,653	331,601
Commercial mortgage-backed securities
Schedule of fair value of trading securities
Debt Securities, Trading	2,114	2,145
Collateralized Mortgage Obligations
Schedule of fair value of trading securities
Debt Securities, Trading	236,139	191,154
Corporate debt securities
Schedule of fair value of trading securities
Debt Securities, Trading	52,536	36,973
States and political subdivisions
Schedule of fair value of trading securities
Debt Securities, Trading	127,955	93,117
Unit investment trusts
Schedule of fair value of trading securities
Debt Securities, Trading		3,468
Private-label securitized product
Schedule of fair value of trading securities
Debt Securities, Trading	6,342	2,992
Other
Schedule of fair value of trading securities
Debt Securities, Trading	$ 3,696	$ 3,446