Deposits - Categorized by Interest-bearing or Noninterest-bearing (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
U.S.:
Interest-bearing	$ 10,193,632	$ 10,129,958
Noninterest-bearing	5,437,919	5,399,212
Foreign:
Interest-bearing	723,999	671,957
Noninterest-bearing	582,628	593,405
Total deposits	$ 16,938,178	$ 16,794,532