Deposits - Categorized by Interest-bearing or Noninterest-bearing (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
U.S.:
Interest-bearing	$ 10,129,958	$ 10,111,319
Noninterest-bearing	5,399,212	4,801,370
Foreign:
Interest-bearing	671,957	618,776
Noninterest-bearing	593,405	530,459
Total deposits	$ 16,794,532	$ 16,061,924