Deposits - Categorized by Interest-bearing or Noninterest-bearing (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
U.S.:
Interest-bearing	$ 9,972,472	$ 10,111,319
Noninterest-bearing	4,926,879	4,801,370
Foreign:
Interest-bearing	647,905	618,776
Noninterest-bearing	574,848	530,459
Total deposits	$ 16,122,104	$ 16,061,924