Acquisitions - Summary of Merger-Related Expenses (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Summary of merger-related expenses
Salaries and employee benefits	$ 371,326	$ 356,551
Equipment and net occupancy	71,167	65,159
Printing, postage and supplies	10,956	10,699
Other costs of operations	223,272	170,406
Hudson City [Member]
Summary of merger-related expenses
Salaries and employee benefits		536
Equipment and net occupancy		201
Printing, postage and supplies		827
Other costs of operations		3,168
Total merger-related expenses	$ 0	$ 4,732