Deposits - Interest-bearing or Noninterest-bearing (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
U.S.:
Interest-bearing	$ 10,158,299	$ 10,393,449
Noninterest-bearing	5,184,816	5,368,729
Foreign:
Interest-bearing	793,465	748,678
Noninterest-bearing	658,664	639,212
Total deposits	$ 16,795,244	$ 17,150,068