Deposits - Interest-bearing or Noninterest-bearing (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
U.S.:
Interest-bearing	$ 11,198,036	$ 9,782,957
Noninterest-bearing	6,084,150	5,188,696
Foreign:
Interest-bearing	791,456	781,965
Noninterest-bearing	824,120	691,376
Total deposits	$ 18,897,762	$ 16,444,994