Note Deposits (Total interest bearing deposits) (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Deposits Abstract
Savings accounts	$ 9,922,817	$ 8,561,718
NOW, money market and other interest bearing demand deposits	12,639,394	10,885,967
Total savings, NOW, money market and other interest bearing demand deposits	22,562,211	19,447,685
Certificates of deposit:
Under $100,000	3,400,596	3,446,575
$100,000 and over	4,022,491	4,068,303
Total certificates of deposit	7,423,087	7,514,878
Total interest bearing deposits	$ 29,985,298	$ 26,962,563