Deposits - Categorized by Interest-bearing or Noninterest-bearing (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
U.S.:
Interest-bearing	$ 10,903,294	$ 10,129,958
Noninterest-bearing	5,227,404	5,399,212
Foreign:
Interest-bearing	677,370	671,957
Noninterest-bearing	644,194	593,405
Total deposits	$ 17,452,262	$ 16,794,532