Note Deposits (Total interest bearing deposits) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Deposits Abstract
Savings accounts	$ 9,161,138	$ 8,561,718
NOW, money market abd other interest bearing demand deposits	11,479,102	10,885,967
Total savings, NOW, money market and other interest bearing demand deposits	20,640,240	19,447,685
Time Deposits Abstract
Under $100,000	3,459,634	3,446,575
$100,000 and over	4,335,609	4,068,303
Total certificates of deposit	7,795,243	7,514,878
Total interest bearing deposits	$ 28,435,483	$ 26,962,563