Summary of Weighted Average Interest Rates for Each Type of Deposit (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Amount
NOW and money market accounts	$ 10,536,947		$ 8,783,795
Savings accounts	5,921,437		4,213,972
Certificates of deposit	6,932,096		9,120,914
Non-interest-bearing accounts	2,270,512		2,758,840
Total deposits	$ 25,660,992		$ 24,877,521
Percent of Total
NOW and money market accounts, percent	41.06%		35.31%
Savings accounts, percent	23.08%		16.94%
Certificates of deposit, percent	27.01%		36.66%
Non-interest-bearing accounts, percent	8.85%		11.09%
Total deposits, percent	100.00%		100.00%
Weighted Average Interest Rate
NOW and money market accounts, weighted average interest rate	0.32%	[1]	0.41%	[1]
Savings accounts, weighted average interest rate	0.44%	[1]	0.31%	[1]
Certificates of deposit, weighted average interest rate	1.16%	[1]	1.18%	[1]
Non-interest-bearing accounts, weighted average interest rate		[1]		[1]
Total deposits, weighted average interest rate	0.54%	[1]	0.63%	[1]

[1] Excludes the effect of purchase accounting adjustments for certificates of deposits ("CDs").